bluez5: add interface access for MediaPlayer application

bluez5: add interface access for MediaPlayer application

MediaPlayer needs to receive a few signals from org.bluez to trigger
various AVRCP metadata and position data.

Change-Id: I5b54f91dc5654d2e0208ae564de2440dc6bd5f48
AGL-Bug: SPEC-541
Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/9125
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: José Bollo <jobol@nonadev.net>
Reviewed-by: Stéphane Desneux <stephane.desneux@iot.bzh>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Reviewed-by: Matt Porter <mporter@konsulko.com>