Allow mixed domain tests to be ignored if no VM the legacy host can use is available

The mixed domain tests won't work properly if the VM running the testsuite is not usable by the legacy host controllers. If the test run is configured with property java8.home set to the root of a JDK 8 installation, then the legacy hosts will be started with JDK 8, which may work. But this has flaws:

• Test jobs may not have java8.home configured, but this suite should still do something reasonable.
• Some legacy host versions it might be better to test with something other than 8, e.g. 11.
• In the future some legacy host versions might not support 8, so we want a more complex mechanism.

To address the first point, the Version.AsVersion enum should include the min and max JVM versions acceptable for that host version. The testsuite in mixed-domain should be ignored if there is a mismatch and the following isn't configured:

The testsuite should check property jboss.test.legacy.host.javaX.home and if set configure the legacy slave to use the VM indicated by the value. The 'X' in 'javaX' is a value between the min and the max value the legacy host version supports. All should be tried until a match is found.