DO NOT MERGE

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.
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:277e7e05866a3da3c5871c071231b2b7c911d81e)
Merged-In: I932d5d5143998db89d7132ced84faffa4a0bd5aa
Change-Id: I932d5d5143998db89d7132ced84faffa4a0bd5aa