ART: Log all monitor operations to systrace

Add a VLOG option ("-verbose:systrace-locks") to log all monitor
operations to systrace. This requires non-fastpath thread
entrypoints, and ATRACE tags for locking and unlocking.

Do a bit of cleanup to the entrypoint initialization to share
common setup.

Bug: 28423466

(cherry picked from commit fc689876)

Change-Id: Ie67e4aa946ec15f8fcf8cb7134c5d3cff0119ab3