pay: Inject channel_hints we receive via plugin notifications

Making sure that we don't accidentally create an endless loop.

plugins/pay.c

@@ -1518,9 +1518,16 @@ static struct command_result *handle_channel_hint_update(struct command *cmd,
 {
 	struct channel_hint *hint = channel_hint_from_json(NULL, buf, param);
 
-	plugin_log(cmd->plugin, LOG_DBG, "Received a channel_hint for scidd=%s",
-		   fmt_short_channel_id_dir(tmpctx, &hint->scid));
-	/* TODO: Apply the change to the channel_hint_set in `hints` */
+	plugin_log(cmd->plugin, LOG_DBG,
+		   "Received a channel_hint {.scid = %s, .enabled = %d, "
+		   ".estimate = %s, .capacity = %s }",
+		   fmt_short_channel_id_dir(tmpctx, &hint->scid), hint->enabled,
+		   fmt_amount_msat(tmpctx, hint->estimated_capacity),
+		   fmt_amount_sat(tmpctx, hint->capacity)
+	);
+	channel_hint_set_add(global_hints, time_now().ts.tv_sec, &hint->scid,
+			     hint->enabled, &hint->estimated_capacity,
+			     hint->capacity, NULL);
 	tal_free(hint);
 	return notification_handled(cmd);
 }