Use appId instead of uid

Multiple user's ares of mApps are not initialized in startMonitoring(),
so mApps.get(uid) of multi-user's app returns null in onPackageAdded().
As the result, permission of system uid is updated to "Network" and
any system application cannot use dedicated apn like IMS.
Using appId avoids this problem.

Bug: 168932048
Test: atest FrameworksNetTests

Signed-off-by: Sangcheol Lee <goodsc.lee@samsung.com>
Change-Id: Ib8ea2185d8056bddb2ca5a8006f83afb3cffc9f4
2 files changed