Be a bit more verbose in the _actions_deferred mon upd handler

In 99df17e we moved the "call
style" argument out of `handle_new_monitor_update`, making each an
individual macro instead. For the
`REMAIN_LOCKED_UPDATE_ACTIONS_PROCESSED_LATER` call style, we
renamed the macro `handle_new_monitor_update_actions_deferred`.
That name doesn't really capture the requirements of that
incredibly-awkward macro - namely that the actions need to be
processed by the caller (rather than just being "deferred" and
handled in some automated way later) and that the macro really
should only be used when the callsite needs the peer state locks to
remain locked, rather than being able to drop them to handle
post-update actions.

Here we rename it to the (mouthful)
`handle_new_monitor_update_locked_actions_handled_by_caller`.
Luckily its only used in two places.

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -3288,8 +3288,9 @@ macro_rules! locked_close_channel {
 	}};
 	($self: ident, $peer_state: expr, $funded_chan: expr, $shutdown_res_mut: expr, FUNDED) => {{
 		if let Some((_, funding_txo, _, update)) = $shutdown_res_mut.monitor_update.take() {
-			handle_new_monitor_update_actions_deferred!($self, funding_txo, update, $peer_state,
-				$funded_chan.context);
+			handle_new_monitor_update_locked_actions_handled_by_caller!(
+				$self, funding_txo, update, $peer_state, $funded_chan.context
+			);
 		}
 		// If there's a possibility that we need to generate further monitor updates for this
 		// channel, we need to store the last update_id of it. However, we don't want to insert
@@ -3741,7 +3742,7 @@ macro_rules! handle_post_close_monitor_update {
 /// drop the aforementioned peer state locks at a given callsite. In this situation, use this macro
 /// to apply the monitor update immediately and handle the monitor update completion actions at a
 /// later time.
-macro_rules! handle_new_monitor_update_actions_deferred {
+macro_rules! handle_new_monitor_update_locked_actions_handled_by_caller {
 	(
 		$self: ident, $funding_txo: expr, $update: expr, $peer_state: expr, $chan_context: expr
 	) => {{
@@ -14360,7 +14361,7 @@ where
 											insert_short_channel_id!(short_to_chan_info, funded_channel);
 
 											if let Some(monitor_update) = monitor_update_opt {
-												handle_new_monitor_update_actions_deferred!(
+												handle_new_monitor_update_locked_actions_handled_by_caller!(
 													self,
 													funding_txo,
 													monitor_update,