Add Material TreeView

[kazo0]

What would you like to be added:

WinUI TreeView Default Style: https://github.com/unoplatform/uno/blob/master/src/Uno.UI/Microsoft/UI/Xaml/Controls/TreeView/TreeView.xaml

WinUI TreeView: https://docs.microsoft.com/en-us/windows/winui/api/microsoft.ui.xaml.controls.treeview?view=winui-2.5

For which Platform:

• [x] UWP
• [x] iOS
• [x] Android
• [x] WebAssembly
• [x] macOS

[mrlacey]

With the Material theme applied, the TreeView doesn't render at all on WASM. It does on Skia (GTK & WPF) - haven't checked others.

[kazo0]

Interesting, we don't have a Material style for TreeView right now