[BH-982] Fix Home Screen issues

- [BH-982] Alarm changing process on home screen should
           start by rotating knob left or right,
- [BH-983] Inactive back button while
           changing alarm on home screen

[EGD-7754] Dates bumped in disclaimers

Dates bumped from 2020 to 2021.

[CP-615] Update existing backup/restore implementation in OS

[CP-648] Handle updated API requests

Updated B&R to handle new API
Extended error reporting
Backup/Restore code clean up

[CP-649] Check OS version compatibility during restore
Added check of OS and backup versions
Fixed adding of version.json to PurePhone.img

[BH-976] Add BGSounds assets path

The proper assets path for application background
sounds added

[BH-1017] Fix BGSounds progress clock

The following commit uses recent BellClock widget
to match current time display to UI design

[BH-992] Correct clock widget in powernap

Correct clock widget in powernap application

[BH-958] Set info screen on critical battery turnoff

Set info screen on critical battery turnoff

[BH-887] Back to homescreen after idle

Back to homescreen after idle

[EGD-7761] Fix HFP reconnect

After connecting to another device while it was connected
HFP didn't disconnect from the previous one

[BH-872] Fix encoder hadnling

interrupt driven encoder handling

[EGD-7085] Third party licenses updated

Updated the third party licenses before the release.

[EGD-6761] Added the C++ coding guidelines

Moved C++ coding guidelines from confluence to repo.

[CP-599] Add crc hash to the last chunk of sent file

CRC was counted in one go before starting to send
chunks of the file, which, in the case of a large file,
caused communication to stop for a long while.
In the current implementation, CRC is counted
incrementally while sending individual file chunks.
It is then appended to the last chunk of the file.

[EGD-7533] Limit [EDG-7533] Limit MTP supported files

MTP supported files are limited to mp3, flac, wav

[EGD-7725] Minor clean ups and removal of dead code

Minor clean ups and removal of dead code

[EGD-7725] Tune up file system io access

Increasd io stream buffers:
- 64kB for big files with short lifetime scope
- 16kB for big files with long lifetime scope
- 1kB - dont changes default forr the rest

[EGD-7675] Sorting/repeating tracks documentation

Add Documentation to describe the implementation concept
for the sort/repeat modes in the music player.

[EGD-7692] Fixing phonebook wording

Changed ICE to emergency and added 'phone' to 'number'

[EGD-7759] Alarm audio duration fix

Alarm audio duration fix. Changed Alarm audio priority.
Fixed SpinBox bottomBar modes.

[EGD-7457] Fix Service antenna based on urc

Not needed AT commands request removed from service antenna.