stagefright: log uri protocols, and opt-in to log full uri

Added property media.stagefright.log-uri.  Set it to true or 1 to
log uris by AwesomePlayer.

Added utility function to get uri debug string based on incognito
and log opt-in status.

Change-Id: I5ccc23079ddfb120dd9703a3ed651a162ed5acec
Related-Bug: 6994761