android/unit: Add android IPC unit tests

It will test ipc library. First test case will check
ipc_init() call.
android/ipc: Remove watches on cleanup

Remove watches on cleanup. It will avoid receiving
events after cleanup.
android/unit: Add /android_ipc/send_cmd_1 test case

This test case will check if ipc lib will raise SIGTERM
after sending command to not registered service.
android/unit: Add /android_ipc/send_cmd_2 test case

This will test sending command to previously registered service.
android/unit: Add /android_ipc/send_cmd_3 test case

This case will register service, next unregister it and send
command. Expected status is raise SIGTERM.
android/unit: Rename tests names to be more descriptive
doc: Add test case numbers from Android IPC unit tests
doc: Minor whitespace fix in test-coverage.txt
android/hal-audio: Remove unsupported mono channel mode

AudioFlinger can only provide PCM 16bit Stereo data for A2DP track so
we should not advertise mono channel mode in capabilities since we
can't downmix this internally.
android/hal-audio: Be more verbose on SBC errors
android/hal-audio: Print calculated SBC parameters
android/hal-audio: Fix audio with large omtu value

This patch fixes media packet construction with devices which use large
omtu value. In such cases it's possible that we will try to fit more
than 15 SBC frames in single media packet (which is maximum possible
value as it's encoded using 4 bits) which will cause frame counter to
wrap around and provide incorrect data to SBC encoder.

This behaviour was seen on UPF with one of carkit devices which set
omtu=2688.
android/hal-audio: Fix RTP sequence numbers
android/hal-audio: Add RTP timestamps
doc: Add experimental GATT API

This patch proposes an unified GATT API for local and remote services.
gatt: Add stub for gatt.{c, h} files

These files implement functions to handle ATT transactions, and expose
functions to allow other entities to manage GATT based services. It
is a replacement for src/attrib-server.c.
gatt: Register Manager D-Bus Interface

This patch registers GATT Service Manager D-Bus Interface. This
interface implements the methods to allow external application register
and unregister GATT Services.
gatt: Add registering external service

This patch allows external applications register a given service on
Bluez. Applications must provide an object path and a dictionary of
options. Options dictionary will be used later to provide additional
service information.
lib: Move GATT UUID to uuid.h

This patch moves GATT UUIDs definitions to a common header. uuid.h contains
helper functions to manipulate Bluetooth UUIDs and some common BR/EDR services
UUIDs.
gatt: Add helper for creating GATT services

This patch adds the btd_gatt_add_service() helper which adds a
GATT Service declaration to the local attribute database.