feat: allow templating in the Signal notificaiton provider (#6989)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Frank Elsinga <frank@elsinga.de>

server/notification-providers/signal.js

@@ -11,8 +11,14 @@ class Signal extends NotificationProvider {
         const okMsg = "Sent Successfully.";
 
         try {
+            let message = msg;
+
+            if (notification.signalUseTemplate) {
+                message = await this.renderTemplate(notification.signalTemplate, msg, monitorJSON, heartbeatJSON);
+            }
+
             let data = {
-                message: msg,
+                message,
                 number: notification.signalNumber,
                 recipients: notification.signalRecipients.replace(/\s/g, "").split(","),
             };