Added missing i18n key for "sponsored" (#10039)

apps/web/src/locales/en/messages.json

@@ -8541,5 +8541,8 @@
   "contactBitwardenSupport": {
     "message": "contact Bitwarden support.",
     "description": "This will be displayed as part of a larger sentence. The whole sentence reads: 'Notice: Later this month, client vault privacy will be improved and provider members will no longer have direct access to client vault items. For questions, please contact Bitwarden support'. 'Bitwarden' should not be translated"
+  },
+  "sponsored": {
+    "message": "Sponsored"
   }
 }