[EGD-5360] Add USB current selection

Charging current selection algorithm
depending on USB type.

[EGD-6214] Add slider position reading after disabling tethering

To be able to set proper phone mode changed by the slider during
tethering, the forced readout of slider position has been added

[EGD-6416] Add handling of headset keys

Change the volume level using headset keys

[EGD-5748] Revert remake cellular flow

Reverts changes due to reported issues

[EGD-6425] Update USB submodule version

Restored USB submodule version to HEAD

[EGD-5443] Onboarding date and time window

Add posibility to override bottom bar in Date and Time settings window.
Change primiary action to save in OnBoardingDateAndTimeWindow
Back to previous window after settings date/time in onboarding flow

[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-6309] Fix 2-sec delay in VCom deinit when USB cable disconnected

When USB wasn't attached, MTP task waits for configured event,
hence it cannot be joined before semaphore take times out (2 sec).

[EGD-6321] Fix max usb current

Setting proper value of
max USB current

[EGD-4863] Add harness test for cellular sleep mode

Adding test for outgoing call and text message
in cellular sleep mode

[EGD-4852] Add sleep mode for GSM modem

When the GSM modem is idle and there is no communication,
it enters the sleep mode, where the power consumption
is significantly reduced.

[EGD-5868] Add access to backup over MTP

This change adds access to backups via MTP
after backup file has been successfuly created.

[EGD-6111] Timers refactored

Deep refactor of system timers.

[EGD-5814] Fix battery revert

Revert of temporary fix
for old battery operation

[EGD-6237] Add memory clearing of MTP database storage

Clear allocated memory to avoid occasional HFs due to accessing
trashed entries

[EGD-6192] Add torch hw control v2

Change behavior of torch
control according to newest
design.

[EGD-4851] Add URC support in sleep mode

When URCs come from the network and GSM is in sleep mode,
we wake up the modem to properly handle the incoming data.

[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.