Only update transaction status to InSidechainBlock after importing block

[haerdib]

Current status:
Upon creating a block and including a specific transaction, the watching client gets notified about the transaction status update InSidechainBlock. However, at this point in time, the block may have been produced, but the state has not yet been updated, nor has the block been broadcasted to other peers.

Task:
Update the transaction status only after importing the block and, therefore, after having updated the state. Otherwise, benchmarking and state queries upon the transaction status change to InSidechainBlock will not return the updated state.