fix: Refactor filter UI and command wiring for AOT compatibility

[w-ahmad]

PR Summary

This PR modularizes the TableView column filter flyout into a dedicated UserControl, streamlines command wiring for header row options, and introduces a new WinUI 3 AOT sample app for testing. The changes enhance maintainability, UX, and AOT compatibility.

• TableViewColumnHeader.cs/xaml: Replaces inline filter flyout with TableViewFilterItemsControl, removes old ViewModel, and refactors filter logic.
• TableViewHeaderRow.cs/xaml: Moves options flyout command wiring to code-behind and updates export menu item visibility logic.
• TableViewFilterItem.cs and ColumnFilterHandler.cs: Adds ShowCount and ValueText properties, updates filter item creation and display logic.
• Adds samples/AotTestApp: New WinUI 3 sample app with MVVM, data faker, and TableView usage, configured for Native AOT.
• Cleans up XAML resources and updates the solution file to include the new sample app.