added missing matrix localization for invitedBy

assets/l10n/intl_en.arb

@@ -2303,6 +2303,12 @@
       "user": {}
     }
   },
+  "invitedBy": "📩 Invited by {user}",
+  "@invitedBy": {
+    "placeholders": {
+      "user": {}
+    }
+  },
   "youInvitedUser": "📩 You invited {user}",
   "@youInvitedUser": {
     "placeholders": {

lib/utils/matrix_sdk_extensions/matrix_locals.dart

@@ -346,8 +346,5 @@ class MatrixLocals extends MatrixLocalizations {
       l10n.startedKeyVerification(senderName);
 
   @override
-  String invitedBy(String senderName) {
-    // TODO: implement invitedBy
-    throw UnimplementedError();
-  }
+  String invitedBy(String senderName) => l10n.invitedBy(senderName);
 }