Feature/rangeslider

[stephenquan]

Description of Change

New Feature: Introduced a RangeSlider control in the CommunityToolkit.Maui library.

Linked Issues

• Fixes Issue [Proposal] RangeSlider #115

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: https://github.com/MicrosoftDocs/CommunityToolkit/pulls - TBA

Additional information

• New Feature Added: Introduced a RangeSlider control in the CommunityToolkit.Maui library.
  • Implemented RangeSlider using two standard Slider controls to leverage built-in keyboard navigation and accessibility features.
  • Added bindable properties for minimum/maximum values, lower/upper values, step size, track colors, thumb colors, and focus mode.
  • Included layout logic for inner and outer tracks and dynamic updates based on user interaction.
  • Implemented focus behavior that tracks the currently focused thumb and adjusts the layout of the underlying slider for improved usability.
• Defaults and Enums:
  • Added RangeSliderDefaults for default values and styling.
  • Added RangeSliderFocusMode enum for thumb focus handling.
• Sample Integration:
  • Registered RangeSliderPage and RangeSliderViewModel in AppShell.xaml.cs and MauiProgram.cs.
  • Added a new sample page (RangeSliderPage.xaml) demonstrating different configurations:
    • Basic slider
    • Slider with step size
    • Descending range (min > max)
    • Custom styling
  • Added RangeSliderViewModel with observable properties for binding.