Improve missing apex_available message

The apex available check can traverse quite a long path (5+ steps) to
get from the apex to a module that is missing the apex from its
apex_available property. Understanding where that dependency came from
can often require examining the dependency path which can be difficult.
This change adds the path to the error to simplify that process.

Test: m nothing
Bug: 152762638
Change-Id: Ic4eb169dc2026cd8339d49e23b25d6d1c3879750