Verify URI permissions in MediaMetadata

Add a check for URI permission to make sure that user can access the URI
set in MediaMetadata. If permission is denied, clear the URI string set
in metadata.

Bug: 271851153
Test: atest MediaSessionTest
Test: Verified by POC app attached in bug, image of second user is not
the UMO background of the first user.

Change-Id: I384f8e230c909d8fc8e5f147e2fd3558fec44626
Merged-In: I384f8e230c909d8fc8e5f147e2fd3558fec44626