media-api: Add playback control methods to MediaPlayer1
media-api: Add playback control methods to MediaPlayer1

This adds methods such as Play, Pause directly in MediaPlayer1, in
addition to that Track is now turn into a property to take advantage of
ObjectManager and document the interface as experimental.

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