Camera2 multi-client

Camera characteristic android.sharedSession.* should only be added
for system cameras.

Flag: com.android.internal.camera.flags.camera_multi_client
Bug:265196098
API-Coverage-Bug: 377371012
Test: In the shared session config xml file add the shared configuration
for all the cameras icnluding public cameras. Verify in dumpsys
media.camera that only system cameras have shared session characteristic
present.

Change-Id: Id8690ed122ce11fc91bc86a0619f98ddc52627ce