Improve MessageMethodArgumentResolver

This commit validates that the payload type of the message is
assignable to the one declared in the method signature. If that
is not the case, a meaningful exception message is thrown with
the types mismatch.

Prior to this commit, only the Message interface could be defined
in the method signature: it is now possible to define a sub-class
of Message if necessary which will match as long as the Message
parameter is assignable to that type.

Issue: SPR-11584