ActivityManagerService: reroute lmkd atoms logging

- Added support to subscribe for a lmkd LMK_ASYNC_EVENT_STAT event
- Added processing LMK_KILL_OCCURRED and LMK_STATE_CHANGED packets
  with logging to statsd
- Added statsd auto-generated code wrapping the statsd logging

Bug: 184698933
Test: lmkd_unit_test - test check_for_oom tests lmkd message send to AMS
Test: statsd_testdrive 51 54 to inspect statsd logged atoms data
Change-Id: I69ef1a9daa5532244a15665bff06d0ad6b370869