OMS: Update PM on main thread with lock

Updating package manager was happening on a handler thread without
obtaining the OMS lock. Rather than lock in the handler thread,
move the communication with PMS to the main thread.

Bug: 180522470
Test: atest OverlayDeviceTests
Change-Id: Id06fc7294cee9db40d34b26807b577ff2b609c37
1 file changed