refactor isAllowedBySettingsLocked()

This commit splits LocationManagerService.isAllowedBySettingsLocked()
into isAllowedByUserSettingsRogkei(), which takes a UID argument, and
isAllowedByCurrentUserSettingsLocked(), which does not. This removes
the need to generate synthetic UIDs with arbitrary application IDs
and makes more explicit when LocationManagerService is acting on
behalf of a caller and when it is acting on behalf of the device's
current active user.

Change-Id: I2cb8fb52687d2629848e5a4b66a4bda8f0f66fe1