android/gatt: Add client read descriptor handler
android/gatt: Add client read descriptor handler

This patch adds descriptor reading. In case of providing wrong
descriptor, error status is being sent with notification.

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