[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-6590] Add /mfgconf mount to iosyscalls lib

Add translation of the /mfgconf mount point in the libiosyscall
library when redirection is disabled.

[EGD-6426] Fix sim card not being detected

Adds selected sim read from settings.

[EGD-6118] BT low power initial implementation

The `Pure`'s power consumption was measured in three variants:
 * BT off
 * BT on (master)
 * BT on (EGD-6118)

Measurement results (respectively):
* idle [mA]:
 ** 78-81
 ** 83-85
 ** 78-81

* BT headphones connected [mA]
 ** -
 ** 85-87
 ** 82-85

* music play [mA] (may be not precise)
 ** 90-100
 ** 98-105
 ** 101-115

[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-3649] Fix paths in UT

Reorganization of assets left path in UT outdated.

[EGD-6313] Fix Display backlight settings are not presistent

Add global scope to settings db function calls

[EGD-6431] Add battery charging temperature ranges

Added actions of several cell temperature
ranges according to requirements.

[EGD-6571] Fix error message

`std::filesystem::remove_all` function returns
number of files and directions removed.
Return value in `cleanupAfterUpdate` from this function
wasn't properly interpreted and returns an error even if shouldn't.

[EGD-6528] Unused keys cleanup from language files

We should not have unused keys now in code

[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-6166] HSP ringing

Added HSP ring sound on incoming call event while
there's bluetooth connection active and HSP is
selected as the current profile.
Possibility of pick up/decline the call using
BT device buttons added.
Slightly changed HSP initialization according
to the UML-s added.
Changed call hangup handler in service cellular.

[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.

[EGD-6573] Fix default audio paths

Default audio paths updated to the newest ones.