[EGD-5737] Merge master into experimental

Keep experimental up to date with changes from master

[EGD-2501] Add gsm powerdown due to battery

Gsm model power state maintenance based on battery level.

Merge branch 'master' into stable

[EGD-4464] Provide GUI for MMI internal messages (#1139)

Merge branch 'master' into stable

[EGD-4465] Create info window for incoming MMI messages (#1078)

[EGD-4466] Create USSD communication window (#1117)

[EGD-3572] SettingsTable exchanged to settings::Settings (#968) (#1044)

[EGD-3572] Application has an instance of Settings - removed from derived apps
[EGD-3572] Application is the owner of Settings handling for its windows/widgets
[EGD-3572] Settings header moved to service-db public section

[EGD-4367] sim passcodes flow implementation (#1033)

Revert "[EGD-3572] SettingsTable exchanged to Settings::Settings (#968)" (#1035)

This reverts commit f11bc1f0d0120c04ee6f826f75c9e8a9f5894602.

Co-authored-by: Hubert Chrzaniuk <hubert.chrzaniuk@mudita.com>

[EGD-3572] SettingsTable exchanged to Settings::Settings (#968)

[EGD-3572] Application has an instance of Settings - removed from derived apps
[EGD-3572] review issues resolved
[EGD-3572] shared_ptr -> unique_ptr
[EGD-3572] Primary Key for settings_tab:path
[EGD-3572] empty values handling

[EGD-4218] Convert service-desktop to library

[EGD-4217] Convert service-db to library

[EGD-4216] Convert service-cellular to library

[EGD-4319] Added test harness API (#993)

[EGD-4319] added phone lock checking and opening application from harness

Co-authored-by: SP2FET <bartosz.cichocki@mudita.com>

[EGD-4200] Message handling refactored. (#974)

[EGD-4288] refactor global data (#959)

Reduce firmware size by refactoring global data defined in public
headers.

Each global variable which require runtime initialization adds
initialization code to every translation unit which includes the header
where the variable is defined and declared.

[EGD-4151] Application manager actions introduced. (#905)

* [EGD-4151] Application manifest structure defined.
* [EGD-4156] Applications registry and basic action handler implemented.

[EGD-4160] renamed PureOS -> MUDITAOS (#901)

[EGD-3743] Update copyrights in fies