A method resolver attempts locate a method and returns a command executor that can be
used to invoke that method. The command executor will be cached but if it 'goes stale'
the resolvers will be called again.
Within the supplied context determine a suitable method on the supplied object that
can handle the specified arguments. Return a MethodExecutor that can be used
to invoke that method, or null if no method could be found.
context - the current evaluation context
targetObject - the object upon which the method is being called
argumentTypes - the arguments that the constructor must be able to handle
a MethodExecutor that can invoke the method, or null if the method cannot be found