Add missing i18n strings (#2181)

src/_locales/en/messages.json

@@ -1845,5 +1845,11 @@
   },
   "removedMasterPassword": {
     "message": "Master password removed."
+  },
+  "leaveOrganizationConfirmation": {
+    "message": "Are you sure you want to leave this organization?"
+  },
+  "leftOrganization": {
+    "message": "You have left the organization."
   }
 }