Update ZeroSharp to .NET 7

[kant2002]

• Has to specify LangVersion becuase version 11 drags requirement on AttributeUsageAttribute
• With runtime does not working, since it missing some bits

  (Code generation failed for method '[Test.CoreLib]System.Runtime.RuntimeExports.RhUnboxNullable(uint8&,MethodTable*,object)') (Code generation failed
  for method '[Test.CoreLib]System.Runtime.RuntimeExports.RhGetCurrentThreadStackTrace(native int[])') (Code generation failed for method '[Test.CoreLib]System.Runtime.EH.RhThrowEx(object,ExInfo&)') (Code gen
  eration failed for method '[Test.CoreLib]System.Runtime.TypeCast.CheckCastInterface(MethodTable*,object)') (Code generation failed for method '[Test.CoreLib]System.Runtime.TypeCast.CheckCast(MethodTable*,ob
  ject)') (Code generation failed for method '[Test.CoreLib]System.Runtime.TypeCast.StelemRef(Array,int32,object)') (Code generation failed for method '[Test.CoreLib]System.Runtime.CachedInterfaceDispatch.Rhp
  ResolveInterfaceMethod(object,native int)') (Code generation failed for method '[Test.CoreLib]System.Runtime.RuntimeExports.RhTryGetThunkData(object,native int,native int&,native int&)')
   ---> ILCompiler.CodeGenerationFailedException: Code generation failed for method '[Test.CoreLib]System.Runtime.RuntimeExports.RhUnboxNullable(uint8&,MethodTable*,object)'
  ---> System.InvalidOperationException: Expected type 'System.RuntimeType' not found in module 'Test.CoreLib'

[MichalStrehovsky]

Thank you! I've updated Test.CoreLib, but we'll probably need to rewrite the RSP file to remove the appcontext switch thing before ILC runs.

[kant2002]

Nice! I like that even better. I do not touch Test.CoreLib because you have no way to validate it if I just put some random bits. It would be more work for you then as it is.