fix: Drop pending finalize messages on disconnected peer

If the peer disconnects before the pending finalize message could have been processed, the recovery logic is in conflict with the hanging message.

Both parties return to the offered state and try to recover from there, now the pending `Finalize` message is out of place.

We had a similar issue with a pending `Confirm` message. I presume this issue got introduced after the protocol was extended for the `Revoke` message.

dlc-messages/src/message_handler.rs

@@ -117,6 +117,16 @@ impl MessageHandler {
                     );
                     false
                 }
+                Message::SubChannel(SubChannelMessage::Finalize(message))
+                if node_id == disconnected_node_id =>
+                    {
+                        log::warn!(
+                        "Dropping SubChannelFinalize message for channel {:?} \
+                         after peer {node_id} disconnected",
+                        message.channel_id
+                    );
+                        false
+                    }
                 Message::SubChannel(SubChannelMessage::CloseConfirm(message))
                     if node_id == disconnected_node_id =>
                 {
@@ -127,6 +137,16 @@ impl MessageHandler {
                     );
                     false
                 }
+                Message::SubChannel(SubChannelMessage::CloseFinalize(message))
+                if node_id == disconnected_node_id =>
+                    {
+                        log::warn!(
+                        "Dropping SubChannelCloseFinalize message for channel {:?} \
+                         after peer {node_id} disconnected",
+                        message.channel_id
+                    );
+                        false
+                    }
                 // Keep any other message
                 _ => true,
             }