[EGD-5158] Change access to the bus methods

The bus is now accessible only via Service object.

[EGD-5575] Add battery file test

Battery file existence test for
harness test suit. Minor changes to
file saving applied.

[EGD-5377] Add USB charger detection

Added USB stack support for detecting connected charger
Added i.MX RT 1051 HW configuration
Added notification to EventManager for detected charger

[EGD-5584] Fix of INTB logs

Deletion of unnecesary log.

[EGD-5390] Add keypad backlight to GUI

Added demo connection to keypad light
GUI window.

[EGD-2514] Fix clock does not refresh

There was no refresh trigger that would cause items like clock
to display its up-to-date state while user is being inactive.
This PR solves that issue providing timer-based refresh trigger
that is dependent on user activity.

[EGD-5367] Add Fuel Gauge parameters

Batery fuel aguge parametrized. Battery charger
parameters also added. Appropriate measurements
added and configured.

Merge branch 'master' into stable

[EGD-5347] Save/load brightness mode

Properly display mode as OnOff switch on screen.

[EGD-5346] Refactor of battery charger BSP

Pure refactoring of battery charger to privide compliance
 with modern C++ standards. Done before implementation of
battery charging algorithms.

[EDG-4717] Add screen for brightness control

Window for manual and automatic screen brightness control.

Merge commit 'c7dd6b399' into stable

[EGD-2501] Add gsm powerdown due to battery

Gsm model power state maintenance based on battery level.

[EGD-5050] Add brownout detection

Brownout detectection realized through charger driver

[EGD-4694] Add CPU frequency shift mechanism

The CPU frequency changes automatically which saves energy

[EGD-4952] Branch fix applied

[EGD-4952] Reverted usage of settings

[EDG-4952] Default value if does not exist in DB.

[EGD-4952] Added stetings for battery critical level

[EGD-4952] Moved battery level check to separate module