[EGD-6514] HSP volume control

Bluetooth headset profile volume control
introduced. Small refactor on A2DP volume control
done.

[EGD-6972] Update BT stack to 1.4.1 version

This PR updates the BT stack to the newest version

[EGD-6882] Fix call hangup after BT device disconnect

Updated the BT stack with events that are handled through the
button so now it's possible to fallback to the earspeaker when
BT connection is lost

Added handling of those events

[BH-515] Create main Bell app

Create main Bell app

Merge branch 'master' into stable

[BH-373] Convert utils json into a lib

Moving json to a third-party standalone library.

[BH-378] PR changes

PR changes - mainly includes

[BH-378] Utils move log to library

Moved log to separate library

Merge branch 'master' into stable

[EGD-6049] Add voice call over HSP

Add support for voice calls over HSP.

Signed-off-by: Marcin Smoczyński <smoczynski.marcin@gmail.com>

[BH-398] Move sml to a separate directory

Move sml to a separate directory

[EGD-6447] Add Bluetooth PIN pairing

Implemented legacy pairing using PIN code

[BH-364] Move TPLIB magic_enum to separate dir

Changed submodule directory and updated cmake scripts and include paths

[EGD-6799] Cleanup audio device interface

This refactoring removes invalid interface dependencies of the original
AudioDevice implementation:
 - move things characteristic to RT1051AudioCodec to audio::codec
 - remove dead methods
 - make start/stop optional and codec configuration independent
 - add more convenient way to get supported formats

Signed-off-by: Marcin Smoczyński <smoczynski.marcin@gmail.com>

[EGD-6674] Change negotiation of audio block size

Replace faulty implementation which produced ambiguous results with one
which is suited for both phone calls and music playback requirements,
including A2DP and HSP Bluetooth profiles.

Signed-off-by: Marcin Smoczyński <smoczynski.marcin@gmail.com>

[EGD-6051] Receiving notifications on bt

Any notification could be heard via bt audio device while
it's connected to the pure.
If any notification is being played and bt device would disconnect,
playback will be stopped.
Disabled bluetooth low power as it was causing issues with the playback.
JIRA for the low power bug
https://appnroll.atlassian.net/browse/EGD-6681 .

[EGD-6513] Volume control feedback

Added volume control feedback during music playback over Bluetooth.
Changed volume buttons handler logic in service audio to use actions
instead of messages.

[EGD-6118] BT low power initial implementation

The `Pure`'s power consumption was measured in three variants:
 * BT off
 * BT on (master)
 * BT on (EGD-6118)

Measurement results (respectively):
* idle [mA]:
 ** 78-81
 ** 83-85
 ** 78-81

* BT headphones connected [mA]
 ** -
 ** 85-87
 ** 82-85

* music play [mA] (may be not precise)
 ** 90-100
 ** 98-105
 ** 101-115

[EGD-6166] HSP ringing

Added HSP ring sound on incoming call event while
there's bluetooth connection active and HSP is
selected as the current profile.
Possibility of pick up/decline the call using
BT device buttons added.
Slightly changed HSP initialization according
to the UML-s added.
Changed call hangup handler in service cellular.

[EGD-6401] Fix bluetooth initialization

Fixed multiple initialization in A2DP and HSP profiles.