Add proper support for 'dotnet run' for mobile targets

[rolfbjarne]

We currently have an incomplete workaround for dotnet/sdk#18436 that makes basic 'dotnet run' support work.

When dotnet/sdk#18436 has been fixed, we should implement something better.

It might be a good idea to look into passing arguments to the app as well at the same time (#14845).

Ref: dotnet/sdk#18436
Ref: #12458

[rolfbjarne]

This is ready to be implemented on our side now, .NET added support for this: dotnet/sdk#42155