Add new location monitoring op, make some of app ops public.

The new location monitoring op is to tell us when an application
is monitoring for any location changes.  It may be useful information
in addition to the more explicitly information about when location
data actually goes to the app.

Also make parts of AppOpsManager public for use by gcore.  It is
not available to third party apps.

Change-Id: Ib639f704258ffdd7f3acd7567350ed2539da628a