Add test for AppDomain.SetData with the same key multiple times

[stephentoub]

Closes https://github.com/dotnet/coreclr/issues/11453
cc: @sepidehms, @AlexGhiondea

[stephentoub]

Blocked on new coreclr coming in

[stephentoub]

@dotnet-bot test this please

[ViktorHofer]

@stephentoub This should be fixed, right? I'm still hitting the issue locally. I cleaned and built everything again today.

System.Tests.AppDomainTests.SetData_SameKeyMultipleTimes_ReplacesOldValue [FAIL]
        System.InvalidOperationException : SetData can only be used to set the value of a given name once.
        Stack Trace:
              at System.AppDomain.SetData(String name, Object data)
           C:\Users\vikto\Documents\src\corefx\src\System.Runtime.Extensions\src\System\AppDomain.cs(150,0): at System.
  AppDomain.SetData(String name, Object data)
           C:\Users\vikto\Documents\src\corefx\src\System.Runtime.Extensions\tests\System\AppDomainTests.cs(271,0): at
  System.Tests.AppDomainTests.SetData_SameKeyMultipleTimes_ReplacesOldValue()

[stephentoub]

Yes, it's fixed.

I cleaned and built everything again today

After pulling down the latest in master? This is a deterministic failure, so if it weren't fixed, we would be seeing all legs in master fail as a result of this.

[ViktorHofer]

Yeah it was with the lastest master bit. Okay, hopefully it won't pop up again for me.

[ViktorHofer]

I just rebuilt everything, it is working now. Thanks!