Deprecate Map Control in favor of MAUI Map implementation

Through https://github.com/dotnet/maui/pull/34138 we have implemented the WinUI MapControl directly in MAUI as of .NET MAUI 10 Service Release 6.

While this one is not on par with Android and iOS it does give the users a way forward to implement the Windows counterpart of this control as well directly through MAUI.

Since Bing maps does not give out any new API keys anymore and now the implementation in MAUI directly, the Map control in the Community Toolkit is of limited use. People might still be using it so I'd recommend to deprecate it for a while first to indicate that it's on its way out.