[CP-206] Report Pure serial number in USB descriptors

Added serial number to USB device descriptor

[EGD-6918] Timestamp clean up

Removal of not needed methods
Addition of unit tests
Fixes according to newst design guidelines
Added new seprate interface cmake lib for time constants

[EGD-5011] Set headphones maximal sound level

In order to pass certification IEC 62368-1, set maximal headphones sound
level accordinly to measurements done by certification laboratory.

[BH-515] Create main Bell app

Create main Bell app

[EGD-6790] Fix cellular sleep mode

Fix of cmux communication in order to
prevent polling thus provide sufficient
time of inactivity to get into sleep mode

Merge branch 'master' into stable

[BH-353] Add Documentation for main targets

* clean up mimimu required cmake version
* fixes for release workflow

Add documentation for targets, fixes for cmake
and release workflow.

[BH-376] Utils time turned to separate library

Turned module-utils/time folder content into separate library,
cleaned up CMake libs dependencies, fixed include paths

[BH-370] Convert utils common_data into a libs

Create clipboard and eventsore libs

[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-6807] Add improved brownout detection

Added immproved battery brownout detection
based on filtered voltage measurement

[EGD-6868] Restore magnetometer polling mode

To be able to properly operate with the slider under every
circumstance the polling mode has to be restored. It's related
to the bug in the magnetometer chip, which is not described in the
datasheet.
This reverts commit 744eef1d9b39cdf2cdbc35f57d6182f5e7942c2f with
few small fixes

[EGD-6843] Fix invalid assert in FSL SNVS driver

Fix an invalid assert after the driver was modified in EGD-6605.

[EGD-6654] Add self-tuning for RC oscillator

Calibrate the RC before switching to the internal oscillator.
This improves the precision of the system clock.

[EGD-6605] Fix RTC time not retained between resets if set manually

When setting datetime from timestamp (manually, not from network),
SRTC is set in order to retain the RTC datetime between resets.

RTC handling was refactored in order to get rid of unnecesary
conversions and third-party code mixed with proprietary code
within a single file.

[CP-88] Pure rejects upload of non-audio files via MTP

Fix handling of UNDEFINED OBJECT for playback formats.

[EGD-6739] Fix Enable change of display resolution on simulator

Define screen dimesions in one place

[EGD-6518] Change optional methods for the DM

Change numer of minimal optional methods required by the
block device in the disk manager

Signed-off-by: Lucjan Bryndza <lucjan.bryndza@mudita.com>