.NET MAUI 9: Better API for Native Embedding

[davidbritch]

In .NET MAUI 9, there's a better API for Native Embedding scenarios. Version the native embedding doc and sample to reflect this.

For more info, see: https://github.com/dotnet/maui/pull/23887 and https://github.com/dotnet/maui/pull/23642

---

Associated WorkItem - 314386