Split LayersTestCase tests of wildfly-ee feature pack layers from tests of wildfly feature pack layers

Our testsuite design is to have testsuite modules that test wildfly-ee feature pack functionality not test wildfly feature pack functionality.[1] The testsuite/layers modules violates this design principle.

So, create a new testsuite/layers-expansion module that tests the wildfly feature pack layers. We're using the term 'expansion' to describe this delta over the wildfly-ee functionality. (The term is shamelessly borrowed from Red Hat JBoss EAP XP.)

 [1]Running the tests against servers provisioned with wildfly feature pack is fine, and is the default behavior. The design consideration is what functionality is tested, not how it is made available in a server.