MethodInvoker should be called with arguments marshalled

[Washi1337]

Summary:
CallBase currently calls the method invoker by passing on the stack ICliValue instances as arguments. It is more advantageous if we pre-marshal the CLI values back to normal CTS values, since this will be a reoccurring theme with future implementations of IMethodInvoker. The proposal is to change CallBase that marshals all arguments to CTS values before dispatching the call to the IMethodInvoker.