bluez5: Unify bt_register_profile_* into a single function

It was a cause of confusion for little gain to have separate
functions for registering profiles with extra information, for
example "role" and "features". We remove those helper functions
in favor of a single one with more parameters, "role" and
"feature" when NULL, will be ignored.
hfp: Add defines for HFP SDP feature bits
hfp_hf_bluez5: Register the SDP record with correct features
handsfree-audio: Fix replying to an empty D-Bus message

In the case that ofono_handsfree_card_connect_sco() is called outside the
context of a .Connect() call, there's no message we need to reply.  This
happens, for example, when the HFP AG plugin initiates a SCO connection when
it receives an AT+BCC command from the HF.
bluetooth: Add define for SCO voice settings

Add defines for SCO voice setting (Air Coding). Air mode "Transparent
Data" shall be supported if wide band speech is supported.
handsfree-audio: Add setting SCO air mode
hfp_hf_bluez5: Handle org.bluez.Profile1.Cancel()

Cancel() will be called when the ConnectProfile() is called, perhaps
even replied with a success, and the user cancels the connection
attempt.
hfp_hf_bluez5: Handle org.bluez.Profile1.Release()

There's nothing we can do in this case, so we only reply with a
success.
test: Create simple-handsfree-audio-agent

This python tool implements the org.ofono.HandsfreeAudioAgent interface,
dealing with the SCO file descriptor passed by the Handsfree Audio
Manager.
include: Add ofono_emulator_create_card()
emulator: Add Handsfree Audio Card to emulator
emulator: Register card when establish SLC
hfp_ag_bluez5: Create card for emulator when connect
emulator: Set local and remote address of card
hfp_ag_bluez5: Pass fd to card creation

We can extract local and remote address from the file descriptor.
emulator: Add init and cleanup functions
main: Call emulator init and cleanup functions
emulator: Add a Card driver for HFP 1.6

This is just the skeleton of a Handsfree Audio Card for the AG side of
HFP 1.6.
emulator: Set card driver

If the version is 1.6, passes the corresponding card driver name. If
not, passes NULL.
hfp_ag_bluez5: Pass HFP version to card creation

Extracts the version from the fd_properties dictionary, if present.
Fallback to HFP version 1.5 if not present.

After that, passes it to the card creation.