Extra option for set_array_state: you choose dirty or clean.
When we first start an array, it might be good to start recovery
straight away. That requires setting the array to 'dirty', but
only the metadata handler can know if that is required or not.
So have a third possible 'consistent' option to set_array_state.
Either 'no' or 'yes' or 'you choose'.
Return value indicates what was chosen.
'1' (no) should be chosen unless there is a good reason.