A PaymentProcess is used to define the way the payment process works as in: what states a Payment can be
in, and how it may transition from one state to another. Using the onTransitionStart() hook, a
PaymentProcess can perform checks before allowing a state transition to occur, and the onTransitionEnd()
hook allows logic to be executed after a state change.
For detailed description of the interface members, see the StateMachineConfig docs.
This is configured via the paymentOptions.process property of
your VendureConfig.
InjectableStrategyTransitions<State, State | PaymentState> & Partial<Transitions<PaymentState | State>>OnTransitionStartFn<State | PaymentState, PaymentTransitionData>OnTransitionEndFn<State | PaymentState, PaymentTransitionData>OnTransitionErrorFn<State | PaymentState>