Earlier CellularDevice has owned event queue used by cellular (state machine and ATHandler for example),
but the thread used to dispatch the queue has been owned by state machine.
This commit moves the event queue thread to CellularDevice so now the ownership of cellular event queue
is in one place.
Simplified state machine by removing manual registering state.
This was done as some modems did not have all the needed at commands
for checking the registered network. Some modem run out of memory as when
checking correct network there might be so many networks available.
Manual registration still works but it does not do any checks to which network
it's registered. Moved manual registering at command earlier in state machine so it forces
registering to a correct network. Internal refactor/fix, does not affect applications.