[ Fluent ] Fix RichTextBox style

[dipeshmsft]

Here are the broad categories of tasks that need to be done per control for this:

• Match resource usage in control styles with WinUI resources where possible
• Add animations for controls where required to match WinUI.
• Compare Fluent styles with Aero2 styles to match
  • Properties like HorizontalAlignment, VerticalAlignment
  • TemplateBinding comparison with Aero2 styles
• Compare WPF Fluent styles with WinUI styles :
  • Convert ControlTemplate Triggers to VisualStates ( to simplify animation's and bring parity with WinUI styles )
  • Convert StaticResource's to DynamicResource for properties where customization is needed.
  • Define resources for CornerRadius, Thickness, etc. for the controls where it is needed