feat(notifications): extension point to modify user resolving

this change adds a new extension point method that can be used to
pass a custom function that can modify how individual user
entity references are resolved inside the notifications backend.

Signed-off-by: Hellgren Heikki <heikki.hellgren@op.fi>

plugins/notifications-node/src/extensions.ts

@@ -100,6 +100,19 @@ export interface NotificationProcessor {
   getNotificationFilters?(): NotificationProcessorFilters;
 }
 
+/**
+ * NotificationRecipientResolver is a function that resolves the individual users to receive the notification
+ * based on the entity reference(s) and the excluded entity reference(s).
+ *
+ * The function should return a list of user entity references that should receive the notification.
+ *
+ * @public
+ */
+export type NotificationRecipientResolver = (
+  entityRef: string | string[] | null,
+  excludeEntityRefs: string | string[],
+) => Promise<string[]>;
+
 /**
  * @public
  */
@@ -107,6 +120,9 @@ export interface NotificationsProcessingExtensionPoint {
   addProcessor(
     ...processors: Array<NotificationProcessor | Array<NotificationProcessor>>
   ): void;
+  setNotificationRecipientResolver(
+    resolver: NotificationRecipientResolver,
+  ): void;
 }
 
 /**