Create a testbom

Add a bom or boms for management of test dependencies, a la what WildFly Core has. Get the test deps out of the root pom.

This should involve a bit of dev list or zulip discussion, as what we have in core has grown kind of organically, so before recreating it we should be clear about the requirements/goals.

The basic goal is to segregate production code deps from test deps and to not have anyone able to use WF's management of test deps for other purposes without making a conscious decision to do so (e.g. by importing our test bom(s)).