refactor: remove duplicate code (#8895)

packages/backend/src/misc/is-user-related.ts

@@ -0,0 +1,15 @@
+export function isUserRelated(note: any, userIds: Set<string>): boolean {
+	if (userIds.has(note.userId)) {
+		return true;
+	}
+
+	if (note.reply != null && userIds.has(note.reply.userId)) {
+		return true;
+	}
+
+	if (note.renote != null && userIds.has(note.renote.userId)) {
+		return true;
+	}
+
+	return false;
+}