Enable recording resource access times

Bug: 246953799

Monitor AssetManager.getResourceValue and AssetManager.retrieveAttributes.
The ResourceTimer loop is started from ResourcesManagerService, which
runs only on system_server.

Publication of the collected resource statistics will be done in a
subsequent commit.  For now, collected statistics values are logged.

Test: atest
 * androidfw_lib

Change-Id: I47b349900429969a6ae8436dc6b00416e9dd76fc