add spacing related suggestion tests

Output is based on the result of:

CSS:

```css
@import "tailwindcss";

@theme {
  --spacing: 0.25rem;
  --spacing-custom: 123px;
}

@Utility with-custom-spacing-* {
  size: --value(--spacing);
}

@Utility with-integer-spacing-* {
  size: --spacing(--value(integer));
}

@Utility with-number-spacing-* {
  size: --spacing(--value(number));
}
```

HTML:

```html
<div class="with-custom-spacing-custom"></div>
<div class="with-custom-spacing-0"></div>
<div class="with-custom-spacing-0.5"></div>
<div class="with-custom-spacing-1"></div>
<div class="with-custom-spacing-1.5"></div>

<div class="with-integer-spacing-custom"></div>
<div class="with-integer-spacing-0"></div>
<div class="with-integer-spacing-0.5"></div>
<div class="with-integer-spacing-1"></div>
<div class="with-integer-spacing-1.5"></div>

<div class="with-number-spacing-custom"></div>
<div class="with-number-spacing-0"></div>
<div class="with-number-spacing-0.5"></div>
<div class="with-number-spacing-1"></div>
<div class="with-number-spacing-1.5"></div>
```

Play: https://play.tailwindcss.com/tYDaSNiNtS

packages/tailwindcss/src/intellisense.test.ts

@@ -476,6 +476,9 @@ test('Custom functional @utility', async () => {
 
       --leading-foo: 1.5;
       --leading-bar: 2;
+
+      --spacing: 0.25rem;
+      --spacing-custom: 123px;
     }
 
     @utility tab-* {
@@ -488,6 +491,18 @@ test('Custom functional @utility', async () => {
       line-height: --modifier(--leading, 'normal');
     }
 
+    @utility with-custom-spacing-* {
+      size: --value(--spacing);
+    }
+
+    @utility with-integer-spacing-* {
+      size: --spacing(--value(integer));
+    }
+
+    @utility with-number-spacing-* {
+      size: --spacing(--value(number));
+    }
+
     @utility -negative-* {
       margin: --value(--tab-size- *);
     }
@@ -515,6 +530,24 @@ test('Custom functional @utility', async () => {
   expect(classNames).not.toContain('-tab-4')
   expect(classNames).not.toContain('-tab-github')
 
+  expect(classNames).toContain('with-custom-spacing-custom')
+  expect(classNames).not.toContain('with-custom-spacing-0')
+  expect(classNames).not.toContain('with-custom-spacing-0.5')
+  expect(classNames).not.toContain('with-custom-spacing-1')
+  expect(classNames).not.toContain('with-custom-spacing-1.5')
+
+  expect(classNames).not.toContain('with-integer-spacing-custom')
+  expect(classNames).toContain('with-integer-spacing-0')
+  expect(classNames).not.toContain('with-integer-spacing-0.5')
+  expect(classNames).toContain('with-integer-spacing-1')
+  expect(classNames).not.toContain('with-integer-spacing-1.5')
+
+  expect(classNames).not.toContain('with-number-spacing-custom')
+  expect(classNames).toContain('with-number-spacing-0')
+  expect(classNames).toContain('with-number-spacing-0.5')
+  expect(classNames).toContain('with-number-spacing-1')
+  expect(classNames).toContain('with-number-spacing-1.5')
+
   expect(classNames).toContain('-negative-1')
   expect(classNames).toContain('-negative-2')
   expect(classNames).toContain('-negative-4')