Smart hint and text box style refactor (#3486)

[adrbarros]

• Initial TextBox style changes added

• Temporarily fix AutoSuggestBox by bringing in old converters directly in style

• Add character counter toggle to demo app

(cherry picked from commit 555d6f9979cb32e004ceb02a716d8fe11ec3d601) (cherry picked from commit 3b61edd)

• Basics of SmartHint refactor in place - edge cases need attention

• Fix "padding" issues for outlined style by letting the padding animate from 0 to desired size

• Fix AcceptsReturn=True scenario for TextBox use of SmartHint

• Smart hint page in demo app handles its own scrolling

• Improve handling of dynamic FontSize changes

• Add TextFieldAssist.IconVerticalAlignment AP to control icon placement in TextBox elements

• Add APs for controlling prefix/suffix visibility and floating hint alignment behavior

• DP cleanup

• Smart Hint demo app page cleanup

• Let hint span accross prefix/suffix texts

• Update demo app Smart Hint page with selectors for new APs

• Make prefix/suffix visibility converter respect new AP

• Decent working state; special cases where hint should also animate horizontally not covered yet

• Fix horizontal animation of hint cases

• Mark converters for obsoletion/deletion

• Remove no longer used converter

• Move SmartHint converters into their own files

• Temporarily change startup page to SmartHint

• Fix FloatingHintInitialHorizontalOffsetConverter logic

• Update MainDemo.Wpf/SmartHint.xaml

• Update MainDemo.Wpf/SmartHint.xaml

• Update MainDemo.Wpf/SmartHint.xaml

• Update MainDemo.Wpf/SmartHint.xaml

• Update MainDemo.Wpf/SmartHint.xaml

• Update MaterialDesignThemes.Wpf/Converters/FloatingHintMarginConverter.cs

• Renamed converter values

• Update MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.SmartHint.xaml

• Implement BooleanToDashStyleConverter.ConvertBack()

• Remove dead code

• Handle HasErrors=True margin correction

• Fix support for TextFieldAssist.NewSpecHighlightingEnabled=True

• Add TextFieldAssist.NewSpecHighlightingEnabled support on demo app SmartHint page

• Add options to control scroll bar visibility on SmartHint demo page (for TextBox variants)

• Slightly nicer layout for scroll bar options on SmartHint demo page

• Fix "accepts return" check box to use VM binding

• Temporarily add defaults to showcase the horizontal scrollbar issue

• Include RD for missing static resource

• PoC fix for the VerticalContentAlignment=Stretch issue

• Fix demo app layout and defaults after rebase

• Leverage list pattern matching in relevant converters

• Cleanup constants and "hide" temporary constants in an internal class.

• Fix for TextBoxTests.FilledTextBox_ValidationErrorMargin_MatchesHelperTextMargin()

• Fix for TextBoxTests.HelperText_CanSetFontColorWithAttachedStyle()

• Fix for TextBoxTests.OnClearButtonShown_ControlHeightDoesNotChange()

• Deleted TextBoxTests.OnOutlinedTextBox_FloatingHintOffsetWithinRange() as it is no longer relevant

• Fix for TextBoxTests.OnTextBoxDisabled_FloatingHintBackgroundIsOpaque()

• Fix for TextBoxTests.OutlinedTextBox_ValidationErrorMargin_MatchesHelperTextMargin()

• Fix for TextBoxTests.TextBox_MultiLineAndFixedHeight_RespectsVerticalContentAlignment()

• Adjust default paddings to for better looks, and temporary make the UI tests comparing control heights pass.

• Merge duplicate triggers

• Add dedicated "MaterialDesign.Brush.TextBox.HoverBorder" brush

• Use new hover brush for the filled TextBox style

• Minor code cleanup

• New brush is now an alternate rather than an obsolete brush

• Fix issue with HintAssist.IsFloating wrongfully affecting the hint text placement

• Cherry-pick FloatingHintMarginConverter from ComboBox branch

• Add additional binding to use of FloatingHintMarginConverter

• Add IsEditable parameter to prefix/suffix converter (taken from ComboBox branch)

• Split failing default height tests into pre- and post-smarthint-refactor

• Fix jumpy UI when validation errors and color hint text red

• Set MinHeight=16 and separate all tests into pre-/post-refactor

• Remove MaxWidth from demo app page

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