Create a picketbox feature pack

We should add a picketbox feature pack to WildFly Core, not included in the dist but built there.

Background:

We include PicketBox in the core pom and the vault functionality core provides requires it but we are not willing to include it in the core dist because it adds ~ 1MB to the dist size.

However, the way we are handling the picketbox module is not clean. The version of two of the jars that end up in the module are declared in the core pom.xml (as they are needed at compile time by core) but the 3rd is specified in full's pom.xml and the module.xml is in full.

We need an org.picketbox module in place to properly test core's vault handling in testsuite/rbac and testsuite/manualmode and there's no real good way to get it into the installations used by those testsuites

Option:

Just add the feature pack maven module as a child of the testsuite maven module, limiting the feature pack use to the testsuite, which is the primary driver of me filing this. That removes any implied requirement to maintain it beyond the needs of the testsuite or to include jars in the generated module beyond what the testsuite needs.