[EGD-4797] Battery bar as widget

Battery bar now is present as
a separate widget in top bar.
Additionally refactored passing
battery status.

[EGD-5382] Add LowPower CpuSentinels

In order to synchronize the Low Power mode, the services were
immediately informed about the frequency change,
so that they can update their resources (e.g. PWM filling)
and services may request the maximum CPU frequency in order
to perform a task (e.g. screen redraw, telephone conversation)

[EGD-5398] Added onBoarding application first version

Created first version of onBoarding application. Added welcome
window, configuration start window and adopted language
window. Small Icon GUI refactor. AppManager language copy removed.

[EGD-4873] Add colors to rt1051 logs

Bring back possibility to get colorful logs from rt1051.
Colored logs can be now turned on in runtime using
Logger::enableColors method.

[EGD-5027] Services synchronization introduced

Dependencies between services are now supported.

[EGD-5381] Add Low Power Drivers

Peripherals clock synchronization dependent on PLL2

[EGD-4955] Add on-off test harness for simulator

This PR provides CI test for turning on and off PurePhone
simulator.

[EGD-5390] Add keypad backlight to GUI

Added demo connection to keypad light
GUI window.

[EGD-3247] Remove reminders of unused ping-pong feature

Feature was already removed some time ago but still some reminders
persist. This commit only removed mentioned reminders.
Some minor style fixes suggested by clang tidy were also applied.

[EGD-4831] Add license headers to c, h and sql files

Add license headers to `h`, `c` and `sql` files as this files haven't
been checked previously, script now to automatically updates current
year in existing licenses.

Merge branch 'master' into stable

[EDG-4717] Add screen for brightness control

Window for manual and automatic screen brightness control.

Merge commit 'c7dd6b399' into stable

Merge branch 'master' into stable

[EGD-2501] Add gsm powerdown due to battery

Gsm model power state maintenance based on battery level.

[EGD-4737] Add VoLTE ON/OFF switch in Settings Network window

Add VoLTE ON/OFF switch in Settings Network window

[EGD-4628] Add APN settings and URC handler for PDP context

Classes supporting APN settings on modem and telephone
configuration (synchronization) have been constructed.
Possibility of asynchronous execution
of individual actions via ServiceCellularAPI.
Added message with information about deactivation of the
PDP context (URC) that the
application / service can listen on.

[EGD-5050] Add brownout detection

Brownout detectection realized through charger driver

[EGD-4978] Add Bluetooth virtual audio device

Bluetooth audio device requires different handling than other
audio devices. The commit adds proxy device that does not
handle requests itself but instead sends requests too Bluetooth
service.

[EGD-4952] Added critical level check + messages