Add support for hosting Blazor Web components directly in WPF (.NET Core)

To simplify some common scenarios we should add support for directly hosting Blazor Web components in WPF (.NET Core) applications. This would use Edge WebView2 directly but still re-use many of the same APIs and patterns used elsewhere in Mobile Blazor Bindings.

The work is to:

1. Factor out much of the hybrid-related code into a new Microsoft.MobileBlazorBindings.Hosting project
2. Change existing MBB to use the new shared Hosting project
3. Create a new Microsoft.MobileBlazorBindings.WPF project that uses WebView2 and the shared Hosting logic

Ideally this wouldn’t change or break any existing MBB applications because all the old APIs should still exist. But there could be a namespace change here or there. We’ll see, but not a big deal.

[IvanJosipovic]

@Jinjinov, its only available in the nightly feed at the moment.

See here, https://docs.microsoft.com/en-us/mobile-blazor-bindings/contribute/nightly-builds

[dcuccia]

For those that land here looking for the latest on the WPF and WinForms BlazorWebView, it arrived today with .NET 6.0 Preview 3:

https://devblogs.microsoft.com/aspnet/asp-net-core-updates-in-net-6-preview-3/