ReturnValueValidator doesn't support Arguments?

[mawosoft]

• ExecutionValidator(Base) has been written before introduction of Arguments and wasn't updated accordingly.
• ReturnValueValidator was written later(?), but is based on ExecutionValidatorBase => no ArgumentsSupport.
  It also uses InProcessNoEmitToolchain.FillMembers() which handles Params only.
• Both call WorkloadMethod.Invoke() with null for arguments.

Not sure if these validators are used anymore. They probably wouldn't have worked for our use case in XmlBenchmarks anyway due to lack of arguments equality (not sure about byte array equality, but ParamWrapper currently is in the way, see mawosoft/Mawosoft.Extensions.BenchmarkDotNet#22).