[EGD-6355] Adjust MuditaOS to be used with Secure Boot

The start address of the OS image adjusted to comply with HAB
Secure Boot. Proper SNVS initialization performed at system startup.
SNVS drivers updated to most recent version. Image signing can be
performed as a part of build process. See doc/secure_boot.md for
more info.

[EGD-6499] Fix audio initialization

Now the peripherals and the audio clocks will be turned on
only when the user is using the audio, which will save energy.

[EGD-5748] Revert remake cellular flow

Reverts changes due to reported issues

[EGD-6156] Create crash dumps

Integrate the CrashCatcher library in order to store phone state after
a fault occurs. The dumps are stored in the CrashCatcher hex format and
can be debugged using the CrashDebug stub built for x86_64 via the
'debug_crash_dump.sh' script.

[EGD-6383] Add HW initialization for headset keys detection

Replaced timer-based hander with IRQ handler to get
  headset status

Added initialization for headset key press detection

[EGD-5748] Remake Cellular flow

This commit changes TS0710 Worker operation.
1. It introduces MessageBuffers as main
interprocess data passing mechanism.
2. DMA transaction status codes and CMUX errors
are now propagated to Service.
3. Data processing has been refactored.

[EGD-5229] Cellular modem, change receiving to DMA

Changes implementation for receiving data from
cellular modem from IRQ byte-by-byte to DMA transactions.
Drop in replacement, works with current CMUX (TS07.10)

[EGD-5101] Add flow control configuration for cellular

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

[EGD-5837] Removed unused cellular pinmux definition

Currently unused.

Merge branch 'EGD-5737-merge-master-to-exp-lbr-fix'

[EGD-5737] Merge master into experimental

Synchronize with master before merging

[EGD-5503] Fix copyright

Previous commit related to the same ticket introduced invalid copyright
in some files. This commit fixes that.

[EGD-5503] Add watchdog implementation

The system watchdog monitors whether there is message traffic
on the Bus. If no message was sent for an extended period of time,
a reset will occur. It should also protect against system-wide hangs.

On Linux, watchdog is simulated by a FreeRTOS task that will call exit
on timeout.

[EGD-5737] Merge master into experimental

Keep experimental up to date with changes from master

[EGD-5737] Merge master into experimental

Keep experimental up to date with changes from master

[EGD-5737] Merge master into experimental

Keep experimental up to date with changes from master

[EGD-5737] Merge master into experimental

Keep experimental up to date with changes from master

[EGD-5102] Fix warning errors in the BSP

Fix warning errors in the BSP module

[EGD-5706] Refactor creating audio device

Audio devices are created in the audio subsystem and it is not possible
to send a device to bt service upon creation.

Introduce hookable audio device factory to allow sharing bluetooth
audio device. Move audio devices from bsp to audio allowing removal of
unwanted bsp -> audio dependency.

Remove Bluetooth proxy device which turned out to be a dead end.

Signed-off-by: Marcin Smoczyński <smoczynski.marcin@gmail.com>

[EGD-5577] Add charger temperature cutoff

Battery charger cutoff due in
selected temperature range. Proper
charged state detection for rt1051