State machine for the round state.
It has following states:
- initial_collateral: The initial collateral state, when the operator didn’t create the first round tx yet.
- round_tx: The round tx state, when the operator’s collateral utxo is currently in a round tx.
- ready_to_reimburse: The ready to reimburse state, when the operator’s collateral utxo is currently in a ready to reimburse tx.
- operator_exit: The operator exit state, when the operator exited the protocol (collateral spent in a non-bridge tx).