[MOS-544] MTP integration issues

* It's now possible to rename files using MTP
* Fixed issue with fs notification being sent from MTP
before file transfer is complete. This resulted in audio
tracks appearing on the MusicPlayer list while still being transferred.

[MOS-776] Deletion of outdated and invalid SettingsApi test

Deletion of outdated and invalid SettingsApi test. New test are planed.

[MOS-651] Update the unread message counter after a thread deletion

In order to delete notification of unread messages
from the thread, which was deleted.
After successful deletion of the thread
the unread messages counter is updated
as when the thread is opened.

[MOS-882] Fix FLAC file playback with USB cable connected

Fix of the issue that caused system crash when
trying to play 96kHz FLAC file with USB cable
connected. The reason of the issue was the lack
of FreeRTOS heap space left, what caused
pvPortMalloc() to fail when allocating
memory for stream buffer.

Additionally minor code cleanup.

[MOS-000] Rebase fixes

Rebase fixes

[MOS-875] Fixed rebase issues

Fixed

[MOS-872] Extended json11 supported types

Moved statvfs to stack from heap

[MOS-872] Add support for directiories in filesystem endpoint's listdir

Added support for listing directiories with nested ones

[MOS-855] Restore process update

Fixed issues with restoring from legacy backups
and cases when the database set fetched from backup package
is different than the system one.

[MOS-853] Purge multimedia database when initializing indexer

When startup indexer for FileIndexer starts, it checks for
lock file. If it's not present, it starts the indexing.

Due to changes in DB initialization we have to purge the
DB before starting the init scan because of potential
restore content

[MOS-856] Another approach to MTP path in DeviceInfo

This time it's device-agnostic from purefs paths

[MOS-855] Fix restore from legacy backup

Added checking if requested to restore backup
from pre-UDM version and setting db versions
to zero in such case, as version info file
(called backup.json in legacy backups) doesn't
contain info about versions.

[MOS-856] Update DeviceInfo documentation

Updated docs for DeviceInfo endpoint

[MOS-856] Add MTP path to DeviceInfo endpoint

Added MTP path for products to enable MC to use it instead
of hardcoded paths

[MOS-852] Fix autolock not working in UDM version

Fix of the issue that in some cases phone
wouldn't lock automatically after given
timeout. This is not a proper fix,
rather a workaround, the whole autolock
mechanism should get refactored to
support testing via harness.

[MOS-851] Remove factory reset screen from backup and restore

Fix of the issue that factory reset screen
informing user of need to manually turn
on the phone to continue the process
was appearing also when restarting to
backup or restore.

[MOS-000] Fixed tests for update

Fixed tests for performing update, now it does not require
developer endpoint

[MOS-000] Bump binaries and add Bell target

Change binary assets versions for both
products, fixed missing dependencies
in Bell's CMake, added 'Bell' target
that automatically builds the
image.

[MOS-807] Removed read code

Removed dead code
Fixed Harmony relaxation app assets path

[MOS-807] Fix MTP root path

Fixed MTP root paths for both Harmony and
Pure due to the MTP implementation
not supporting hierarchical directories.