unit/test-hfp: Add init test for HFP HF
unit/test-hfp: Add init test for HFP HF

This patch adds basic infrastruction for HFP HF test plus
init test.

It also moves send_pdu function in the file so it can be used by
test_hf_handler

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