peer: update rbf close client logic w/ error and iteration awareness

We'll properly handle a protocol error due to user input by halting, and
sending the error back to the user.

When a user goes to issue a new update, based on which state we're in,
we'll either kick off the shutdown, or attempt a new offer. This matches
the new spec update where we'll only send `Shutdown` once per
connection.

lnwallet/chancloser/rbf_coop_states.go

@@ -959,3 +959,7 @@ type RbfState = protofsm.State[ProtocolEvent, *Environment]
 
 // RbfEvent is a type alias for the event type of the RBF channel closer.
 type RbfEvent = protofsm.EmittedEvent[ProtocolEvent]
+
+// RbfStateSub is a type alias for the state subscription type of the RBF chan
+// closer.
+type RbfStateSub = protofsm.StateSubscriber[ProtocolEvent, *Environment]