Refactor EJB client affinity processing

Refactor of jboss-ejb-client internal operation: change the way in which proxy affinity (an object that decides on which node invocation should be performed) is determined. Instead of calculating it on client side we would let server set the affinity when necessary and propagate it to the client.

This refactor is supposed to reduce the complexity of jboss-ejb-client code and as a result, make it significantly easier to maintain. Richard has prepared a comprehensive document describing the suggested modifications: https://mojo.redhat.com/docs/DOC-1204767

Parallelly, the test suite has to be refactored to make it compatible with the new algorithm and to provide broad coverage of jboss-ejb-client operation.