Pass the media capabilities uid when opening media

FileSystemProvider should pass the uid of the calling app by setting
the EXTRA_MEDIA_CAPABILITIES_UID when opening a media, so that
TranscodeHelper can make decision to transcode or not transcode based on
the calling uid, and not based upon the Provider's uid.

BUG=176157500
Test: manual testing.

Change-Id: Ie08b94cf79c86e9f87639e4fbdd82b2732771187