[internal]: Validate response signature (#15736)

* [internal]: Validate response signature

We add the error message here for validating response signature

* Trigger CI

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

i18n/en.json

@@ -6194,6 +6194,10 @@
     "id": "ent.saml.do_login.empty_response.app_error",
     "translation": "We received an empty response from the Identity Provider."
   },
+  {
+    "id": "ent.saml.do_login.invalid_signature.app_error",
+    "translation": "We received an invalid signature in the response from the Identity Provider. Please contact your System Administrator."
+  },
   {
     "id": "ent.saml.do_login.parse.app_error",
     "translation": "An error occurred while parsing the response from the Identity Provider. Please contact your System Administrator."