Mark the org.jboss.msc module as jboss.api=deprecated

In the long run we prefer that application code not use the JBoss MSC APIs so we should deprecate the module so such uses are informed via a log WARN.

Also, add a comment about the jboss.api property noting that MSC includes deprecated API that may be removed in a later minor release. The MSC 1.x APIs have been deprecated for many years now and are on a pretty clear path toward removal.