shared/gatt: Add initial implementation of discover_included_services
shared/gatt: Add initial implementation of discover_included_services

Current implementation allow to discover included services with
16 bit UUID only.

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