Add utilities to provide empty deployments for tests that are conditionally ignored

As discussed in https://wildfly.zulipchat.com/#narrow/stream/174184-wildfly-developers/topic/Arquillian.20Ignoring.20ServerSetupTask.20Failure/near/270394410, the ARQ lifecycle is such that if you want to conditionally ignore a test class, there's no good way to stop ARQ deploying in @Deployment artifacts before your code runs to disable the test. So let's add utils that @Deployment methods can conditionally call to get quick empty deployments.

This may prove mostly irrelevant in the medium term if we improve how WFARQ handles throwables in ServerSetup classes, but since I already wrote the code for this for use in some maintenance branches, might as well port it to main. It may help during EE 10 work, e.g. with WFLY-16056.