[Skia] Add support for `WebView`

[jeromelaban]

What would you like to be added:

Support for the WebView control when using the Skia backend.

Related:

• https://webkitgtk.org/
• https://github.com/webview/webview
• https://github.com/GtkSharp/GtkSharp/pkgs/nuget/WebkitGtkSharp/

For which Platform:

• [ ] iOS
• [ ] Android
• [ ] WebAssembly
• [ ] WebAssembly renderers for Xamarin.Forms
• [ ] macOS
• [x] Skia
  • [x] WPF
  • [x] GTK (Linux)
  • [ ] Tizen
• [ ] Windows
• [ ] Build tasks
• [ ] Solution Templates

Anything else we need to know?

[MartinZikmund]

Worth checking - https://github.com/webview/webview

[IneedHelp]

As requested, I'll add here what I wrote on the Uno Discord, general-chat: Uno devs, do you think we'll ever have a "DotNetBrowser Meets Uno"? [ https://avaloniaui.net/Blog/dotnetbrowser-meets-avalonia ] I believe WebView2 is the closest thing to it that we have right now, but DotNetBrowser is on a whole new level. I used it a lot in my WPF projects, would be amazing to see you guys partner with them and bring that to Uno

More about DotNetBrowser's capabilities on their website: https://dotnetbrowser-support.teamdev.com/