Consider basic support for launchSettings for the new dotnet test

[Youssef1313]

I suggest to at least support environment variables and command line arguments from launchSettings.

If we take it out from .NET 10 and introduce the support for .NET 11, it will be a breaking change. So we might never be able to add the support if it's not in .NET 10 when the new dotnet test experience for MTP is first shipped.

Related to #45927

[Evangelink]

I think that's a good idea. Given dotnet run supports it, I wonder if you could reuse/uplift most of the code and so get close to 100% support quickly.

[Youssef1313]

Perfect!

@drognanar FYI as we will likely need similar support in TE if this was done in dotnet test.