Split the MAUI build/pack into its own process

[rockfordlhotka]

Because .NET MAUI has a separate release cycle from .NET itself, the Csla.Xaml.Maui project and NuGet package also needs to have a separate release cycle from the rest of CSLA.

@Bowman74 has some good insights into this in #4349

I think it will require

• Pulling the Csla.Xaml.Maui project out of the csla.build solution
• Changing Csla.Xaml.Maui.csproj to reference CSLA via NuGet instead of as a project reference
• Creating a new solution specifically for building the CSLA MAUI project
• Creating a new GitHub action yaml file to build/pack/push the CSLA MAUI project