[WIP] feat: Replace Generic.xaml resources with WinUI styles

[MartinZikmund]

GitHub Issue: closes #12839

PR Type: ✨ Feature, 🐞 Bugfix

What is the current behavior? 🤔

• Generic.xaml is significantly outdated

What is the new behavior? 🚀

• Updating to latest Generic.xaml from WinUI

PR Checklist ✅

Please check if your PR fulfills the following requirements:

• 📝 Commits must be following the Conventional Commits specification.
• 🧪 Added Runtime tests, UI tests, or a manual test sample for the changes have been added (for bug fixes / features) (if applicable)
• 📚 Docs have been added/updated which fit documentation template (for bug fixes / features)
• 🖼️ Validated PR Screenshots Compare Test Run results.
• ❗ Contains NO breaking changes

Other information ℹ️

[Copilot]

Pull Request Overview

This PR replaces Generic.xaml resources with WinUI styles by removing platform-specific style declarations from TwoPaneView and ScrollViewer/ScrollBar XAML files and improving error messaging in the XAML generator.

• Removes entire TwoPaneView_v1.xaml and TwoPaneView_rs1.xaml resource files
• Eliminates platform-specific style declarations from ScrollViewer and ScrollBar XAML files
• Enhances error messaging in XamlFileGenerator to include property and type information

Reviewed Changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
TwoPaneView_v1.xaml	Complete removal of TwoPaneView style definitions and resource dictionary
TwoPaneView_rs1.xaml	Complete removal of TwoPaneView style definitions (already commented out)
ScrollViewer.xaml	Removes platform-specific style declarations at end of file
ScrollBar.xaml	Removes platform-specific style declarations at end of file
XamlFileGenerator.cs	Improves error message to include property name and type information

[unodevops]

🤖 Your WebAssembly Skia Sample App stage site is ready! Visit it here: https://unowasmprstaging.z20.web.core.windows.net/pr-21513/wasm-skia-net9/index.html

[unodevops]

🤖 Your Docs stage site is ready! Visit it here: https://unodocsprstaging.z13.web.core.windows.net/pr-21513/docs/index.html

[unodevops]

🤖 Your WebAssembly Skia Sample App stage site is ready! Visit it here: https://unowasmprstaging.z20.web.core.windows.net/pr-21513/wasm-skia-net9/index.html

[unodevops]

🤖 Your Docs stage site is ready! Visit it here: https://unodocsprstaging.z13.web.core.windows.net/pr-21513/docs/index.html