tools/bluetooth-player: Add proxy handling for org.bluez.MediaItem1
tools/bluetooth-player: Add proxy handling for org.bluez.MediaItem1

This adds proxy handling for org.bluez.MediaItem1 so changes to the
proxy are printed in the output.

mapfau/bluez,ComputeCycles/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,silent-snowman/bluez,mapfau/bluez,pkarasev3/bluez,silent-snowman/bluez,mapfau/bluez,silent-snowman/bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,silent-snowman/bluez,pkarasev3/bluez,pkarasev3/bluez,ComputeCycles/bluez,mapfau/bluez