Fix chip widgets don't the apply provided iconTheme (#135751)

fixes [`Chip.iconTheme` does not apply the icon theme](flutter/flutter#111828)

### Description
- Fix chip widgets that don't utilize the provided `iconTheme`.
- Prevent `iconTheme` with just color from overriding the default icon size.
- Add some missing M3 tests for the chip and chip theme properties.

### Code sample

<details>
<summary>expand to view the code sample</summary> 

```dart
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @OverRide
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(useMaterial3: true),
      home: const Example(),
    );
  }
}

class Example extends StatefulWidget {
  const Example({super.key});

  @OverRide
  State<Example> createState() => _ExampleState();
}

class _ExampleState extends State<Example> {
  final bool _isEnable = true;

  @OverRide
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: <Widget>[
            RawChip(
              iconTheme: const IconThemeData(color: Colors.amber),
              avatar: const Icon(Icons.favorite_rounded),
              label: const Text('RawChip'),
              onPressed: () {},
              isEnabled: _isEnable,
            ),
            const Chip(
              iconTheme: IconThemeData(color: Colors.amber),
              avatar: Icon(Icons.favorite_rounded),
              label: Text('Chip'),
              // onDeleted: () {},
            ),
            FilterChip(
              iconTheme: const IconThemeData(color: Colors.amber),
              avatar: const Icon(Icons.favorite_rounded),
              label: const Text('FilterChip'),
              selected: false,
              onSelected: _isEnable ? (bool value) {} : null,
            ),
            InputChip(
              iconTheme: const IconThemeData(color: Colors.amber),
              avatar: const Icon(Icons.favorite_rounded),
              label: const Text('InputChip'),
              isEnabled: _isEnable,
              onPressed: () {},
            ),
            ActionChip(
              iconTheme: const IconThemeData(color: Colors.amber),
              avatar: const Icon(Icons.favorite_rounded),
              label: const Text('ActionChip'),
              onPressed: _isEnable ? () {} : null,
            ),
            ChoiceChip(
              iconTheme: const IconThemeData(color: Colors.amber),
              avatar: const Icon(Icons.favorite_rounded),
              label: const Text('ChoiceChip'),
              selected: false,
              onSelected: _isEnable ? (bool value) {} : null,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {},
        child: const Icon(Icons.add),
      ),
    );
  }
}

```

</details>

### Before
![Screenshot 2023-09-29 at 16 59 39](https://github.com/flutter/flutter/assets/48603081/4bc32032-cff3-4237-812f-86f17ed95337)

### After

![Screenshot 2023-09-29 at 16 55 24](https://github.com/flutter/flutter/assets/48603081/05a1fc52-fb31-4790-a840-18f2e9718241)

Author: TahaTesser

packages/flutter/lib/src/material/action_chip.dart

@@ -225,6 +225,7 @@ class ActionChip extends StatelessWidget implements ChipAttributes, TappableChip
       elevation: elevation,
       shadowColor: shadowColor,
       surfaceTintColor: surfaceTintColor,
+      iconTheme: iconTheme,
     );
   }
 }

packages/flutter/lib/src/material/chip.dart

@@ -659,6 +659,7 @@ class Chip extends StatelessWidget implements ChipAttributes, DeletableChipAttri
       elevation: elevation,
       shadowColor: shadowColor,
       surfaceTintColor: surfaceTintColor,
+      iconTheme: iconTheme,
     );
   }
 }
@@ -1219,7 +1220,10 @@ class _RawChipState extends State<RawChip> with MaterialStateMixin, TickerProvid
     final Color? resolvedLabelColor = MaterialStateProperty.resolveAs<Color?>(effectiveLabelStyle.color, materialStates);
     final TextStyle resolvedLabelStyle = effectiveLabelStyle.copyWith(color: resolvedLabelColor);
     final Widget? avatar = iconTheme != null && hasAvatar
-      ? IconTheme(data: iconTheme, child: widget.avatar!)
+      ? IconTheme.merge(
+          data: theme.useMaterial3 ? chipDefaults.iconTheme!.merge(iconTheme) : iconTheme,
+          child: widget.avatar!,
+        )
       : widget.avatar;
 
     Widget result = Material(

packages/flutter/lib/src/material/filter_chip.dart

@@ -235,6 +235,7 @@ class FilterChip extends StatelessWidget
       showCheckmark: showCheckmark,
       checkmarkColor: checkmarkColor,
       avatarBorder: avatarBorder,
+      iconTheme: iconTheme,
     );
   }
 }

packages/flutter/lib/src/material/input_chip.dart

@@ -236,6 +236,7 @@ class InputChip extends StatelessWidget
       checkmarkColor: checkmarkColor,
       isEnabled: isEnabled && (onSelected != null || onDeleted != null || onPressed != null),
       avatarBorder: avatarBorder,
+      iconTheme: iconTheme,
     );
   }
 }

packages/flutter/test/material/action_chip_test.dart

@@ -44,6 +44,16 @@ Material getMaterial(WidgetTester tester) {
   );
 }
 
+IconThemeData getIconData(WidgetTester tester) {
+  final IconTheme iconTheme = tester.firstWidget(
+    find.descendant(
+      of: find.byType(RawChip),
+      matching: find.byType(IconTheme),
+    ),
+  );
+  return iconTheme.data;
+}
+
 DefaultTextStyle getLabelStyle(WidgetTester tester, String labelText) {
   return tester.widget(
     find.ancestor(
@@ -349,4 +359,29 @@ void main() {
     await tester.pumpWidget(wrapForChip(child: ActionChip(label: label, clipBehavior: Clip.antiAlias, onPressed: () { })));
     checkChipMaterialClipBehavior(tester, Clip.antiAlias);
   });
+
+  testWidgetsWithLeakTracking('ActionChip uses provided iconTheme', (WidgetTester tester) async {
+    Widget buildChip({ IconThemeData? iconTheme }) {
+      return MaterialApp(
+        home: Material(
+          child: ActionChip(
+            iconTheme: iconTheme,
+            avatar: const Icon(Icons.add),
+            onPressed: () { },
+            label: const Text('action chip'),
+          ),
+        ),
+      );
+    }
+
+    // Test default icon theme.
+    await tester.pumpWidget(buildChip());
+
+    expect(getIconData(tester).color, ThemeData().colorScheme.primary);
+
+    // Test provided icon theme.
+    await tester.pumpWidget(buildChip(iconTheme: const IconThemeData(color: Color(0xff00ff00))));
+
+    expect(getIconData(tester).color, const Color(0xff00ff00));
+  });
 }

packages/flutter/test/material/chip_test.dart

@@ -3570,6 +3570,40 @@ void main() {
     );
   });
 
+  testWidgetsWithLeakTracking('Material3 - Chip.iconTheme respects default iconTheme.size', (WidgetTester tester) async {
+    Widget buildChip({ IconThemeData? iconTheme }) {
+      return MaterialApp(
+        theme: ThemeData(useMaterial3: true),
+        home: Directionality(
+          textDirection: TextDirection.ltr,
+          child: Material(
+            child: Center(
+              child: RawChip(
+                iconTheme: iconTheme,
+                avatar: const Icon(Icons.add),
+                label: const SizedBox(width: 100, height: 100),
+                onSelected: (bool newValue) { },
+              ),
+            ),
+          ),
+        ),
+      );
+    }
+
+    await tester.pumpWidget(buildChip(iconTheme: const IconThemeData(color: Color(0xff332211))));
+
+    // Icon should have the default chip iconSize.
+    expect(getIconData(tester).size, 18.0);
+    expect(getIconData(tester).color, const Color(0xff332211));
+
+    // Icon should have the provided iconSize.
+    await tester.pumpWidget(buildChip(iconTheme: const IconThemeData(color: Color(0xff112233), size: 23.0)));
+    await tester.pumpAndSettle();
+
+    expect(getIconData(tester).size, 23.0);
+    expect(getIconData(tester).color, const Color(0xff112233));
+  });
+
   group('Material 2', () {
     // These tests are only relevant for Material 2. Once Material 2
     // support is deprecated and the APIs are removed, these tests