feat(XamlBasics): Add ThreeLevelListDetailSampleApp

[lukeblevins]

Adds relevant sample for Xaml Basics writeup write up

Discussed internally with @sasakrsmanovic and Matthew M.

[lukeblevins]

This is the sample for https://platform.uno/blog/xaml-fundamentals-for-web-and-mobile-three-level-list-detail-pattern/

Uno Platform

XAML Fundamentals for Web and Mobile: Three-level List/Detail Pattern

Pixel-Perfect Multi-Platform Applications with C# and WinUI for Windows, WebAssembly, iOS, macOS, Android and Linux

[nickrandolph]

@lukeblevins a couple of comments:

• Is there a reason we've only included the Win/Wasm targets?
• Let's see if we can rework the logic to avoid as much code behind and just use data binding where possible
• Let's fix the CI to make sure the sample is building

[nickrandolph]

@lukeblevins what's left to be done on this PR?

[nickrandolph]

@lukeblevins as discussed, I've closed this PR - please reopen it once you have a chance to update the code