[EGD-5101] Add flow control configuration for cellular

Fix flow control pin configuration in OS.
Turn on flow control for cellular modem.

[EGD-6197] Unify settings menu text labels

Unifying setting menu text labels when it comes
to capital and small letters.

[EGD-6196] Replace venv command in harness readme

Replaced to avoid usage of python2

[EGD-5490] Add BT pairing documentation

Documentation gives a high-level overview of the following procedures:
-scanning
-pairing
-unpairing

[EGD-5989] Update quickstart article

Updated quickstart article with security-related info.

[EGD-5989] Update quickstart.md

Fixed a bit of a security risk.

[EGD-5965] Add BT-Harness API documentation

Added documentation:
* BT endpoint API
* BT-Harness tests

[EGD-6008] Create Pure flashing guide

Added small changes after trying to
boot the image on my own.

[EGD-6092] Create Pure flashing guide

Fixed some lines in the docs

[EGD-6092] Create Pure flashing guide

Ported Pure flashing guide on macOS/Win
to GitHub.

Co-authored-by: Michał Kamoń
<70628259+mkamonMdt@users.noreply.github.com>

[EGD-6092] Create Pure flashing guide

Ported Pure flashing guide macOS/Win to GitHub.

[EGD-5658] Add eInk CPU frequency hold

While the screen is being redrawn,
we block CPU frequency decreasing

[EGD-6150] Clean bottom bar after unpairing last device from the list

FORGET and CONNECT/DISCONNECT buttons were not removed after
the last device was removed from the list in All Devices window.

[EGD-6144] Fix bluetooth settings window after changing phone visibility

Bluetooth settings window was displayed incorrectly after
changing phone visibility.

[EGD-5449] Add final prompts windows

Added Dialog windows for "configuration successful"
"no configuration" and "update OS" for Onboarding.
Refactor Dialog window implementation and usage of
DialogMetadata in other applications.

[EGD-6130] Fix update process (stack size, fscopy)

Increase stack size for service-desktop to 8192
Change fs syscall rename() to copy() (rename seems
to fail when moving data across different filesystems)

[EGD-6131] Fix modem startup

Fix modem start issue
due to bug in battery
level check.

[EGD-5624] Added window update

This PR introduces mechanism for passing
data to the currently displayed window by
switch data.

Merge branch 'stable' - release 0.59.1

[EGD-5902] Phone Modes Windows

Windows for phone modes created.
Offline:FightMode/messages only ServiceCellularApi created.
ConnectionFrequency and DND options settings throught AppSettings.