[EGD-6495] Add pause/resume/stop to MP

Added basic Pasue/Resume/Stop actions to confirm
that related Audio service operations work

Added handling of headset OK for Pause/Resume/Stop actions
while in Music Player

[EGD-6064] Add connecting and pairing bluetooth states

Pairing and connecting states are now visualized
in All devices window to inform phone user what is happening.

[EGD-5776] Replace incorrect block contact icon with the correct one

Replace incorrect block contact icon with the correct one.

[EGD-6613] Audio assets tags are not displayed

When selecting ring/sms/notification sound the title from audio tags is
displayed. If tags are empty the filename is shown.

[EGD-5849] Make calculator compute previous operations

Modify calculator behavior according to PO input:
* Compute existing equation before entering next operation
* Limit digit input to 7 digits
* Start each number input from empty input

[EGD-6337] Add desktop tethering notification

This PR adds home screen tethering notification. The notifications
allows user to disconnect tethering from desktop by focusing on
the notification and pressing `KEY_ENTER`

This PR adds also home screen notifications icons in `.png` format.
Icons shall be converted to `.vpi` and used in other tasks regarding
home screen notifications.

[EGD-6606] Fix the sound for meditation app

Added sound media as separate file, and changed path for it in code.

[EGD-6456] ListView based desktop notification

This PR provides following changes in notifications:
- notifications were extracted as widget for pop-up-based
locked-screen implementation
- notifications are ListView based implemented
- the most recent notification is displayed on the top of the list

[EGD-6513] Volume control feedback

Added volume control feedback during music playback over Bluetooth.
Changed volume buttons handler logic in service audio to use actions
instead of messages.

[EGD-6506] Turn on function keys backlight during call

Backlight of function keys are on when call is active.
When call ends, previous backlight mode is restored.

[EGD-6452] Sound selection GUI

Sound selection GUI used to change ringtone, message sound and
notification sound in settings.

[EGD-6563] Don't allow to edit exponent output in calculator

Clear the calculator input field before typing if it contains exponent
output from previous calculations.

[EGD-6301] Add Connecting to the network in intervals

It implements mode Offline Messages only - connecting to
the GSM network in defined by user intervals and rejecting
incomig calls during connected phase. It also implements
handling of connetion interval setiing and small fix in modes
popup.

[EGD-5773] Device becomes not responsive when opening settings

Use asynchronous communication with service cellular
to obtain own number.

[EGD-6426] Fix sim card not being detected

Adds selected sim read from settings.

[EGD-6527] Internationalization API unification

Single api to rule i18n
all calls to localistaion in cpp files unified
cut off ass many dependencies in i18n header as possible

[EGD-6485] Remove Cellular message types from global

Domain-specific message types should not pollute global space.

[EGD-6561] Limit calculator decimals to 6 digits

Limit to 6 since our `utils::to_string(double)' function also
limits to 6 decimals.

[EGD-6561] Make calculator input testable

I got sick of manually testing calculator like a troglodyte.

[EGD-6575] Rename Unicast with timeout as UnicastSync

Using Unicast with timeout is dangerous and strongly discouraged.
This change allows for more precise tracking of such cases.