Fix bugs in LocationManagerService and AppOpsPolicy

LocationManagerService was overwriting location source appops tag
information whenever a location provider changed state. Since multiple
location providers can correspond to the same uid/app id, this could
lead to loss of tags. This is fixed by recalculating the set of tag for
an entire app id any time a uid changes.

AppOpsPolicy had a bug where tag lists coming from different uids under
the same appid would inappropriately overwrite each other. This is fixed
by modifying the internal/external APIs to work in terms of appid rather
than uid, so that it is someone else's responsibility to ensure the
result is valid for the app id as a whole.

Also fixes a bug where LMS assumes tag listeners are added prior to any
providers. If listeners are added after some providers they will miss
updates. Fixed by always updating the listener on registration.

Bug: 190073375
Test: manual
Change-Id: Ib52d752d857b6ac3b6683186a8d1bbcb814fb798