Preserve permissions when system apps leaving shared UID are uninstalled

This is a follow up of ag/15936308.

When a system app update is uninstalled, the permission states are
preserved. However, in the case of system apps leaving shared UID
through an update, due to the fact that the appId has changed, the
permission states will be lost, causing issues specifically with certain
permission flags.

In this CL, we add a new method in PermissionManagerService to handle
this specific case. The permissions are either cloned to the previous
appId, or merged into the UidPermissionState of the shared UID group.

Test: tracking with b/202993696
Bug: 179284822
Change-Id: I02894671f1b8357fbb347c8daf7c1167ae051ac6