Add offer status in check_offer_validity response

[mikehw]

It would be useful to have the offer's status (e.g. accepted vs canceled) returned in the check_offer_validity response. This way the offer does not need to be in the wallet's trade_manager to determine if the offer was accepted vs canceled.

This is useful for deploying an offer record-keeping system in a micro-service architecture where there isn't a single chia wallet that has all of the offers loaded into the trade manager.

[mikehw]

It would also be useful to know the height when the status changed.