Fix syncing back to at mode after ppp disconnect.
Fix AT_CellularContext flags and states to allow new connect after disconnect.
Fix that state machine is not reseted in disconnect is it's running (might be
running because of another context or new connect already started).
There are two EventQueue.h in mbed-os codebase:
events/EventQueue.h
features/FEATURE_BLE/ble/pal/EventQueue.h
By accident, `mbed compile` generates includes.txt with the correct
order of include search paths. This is not the case for the CMake
exporter: targets with FEATURE_BLE enables fail to compile with errors:
mbed-os/features/cellular/framework/AT/ATHandler.h:99:60: error:
'events' has not been declared
Update all places to always include either "events/EventQueue.h"
or "ble/pal/EventQueue.h": to always find the correct header.
Moved methods to classes CellularDevice and CellularInformation.
SIM interface was removed to simplify cellular usage and
methods better suite new classes.
Updated greentea and unit tests.