test: Add support for using external player
test: Add support for using external player

This add support for passing a device player object which is then
registered as a local one in a loopback fashion.

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