Merge pull request #15683 from overleaf/ab-group-sso-identity-already-exists-error

[web] Show an explicit error when the identity is already attached to another account

GitOrigin-RevId: 4eb3f4dcc43d6dec3483dfa83b98ea18466fe335

services/web/frontend/extracted-translations.json

@@ -996,6 +996,7 @@
   "right": "",
   "role": "",
   "saml_auth_error": "",
+  "saml_identity_exists_error": "",
   "saml_invalid_signature_error": "",
   "saml_login_disabled_error": "",
   "saml_login_failure": "",

services/web/locales/en.json

@@ -1519,6 +1519,7 @@
   "saml": "SAML",
   "saml_auth_error": "Sorry, your identity provider responded with an error.  Please contact your administrator for more information.",
   "saml_create_admin_instructions": "Choose an email address for the first __appName__ admin account. This should correspond to an account in the SAML system. You will then be asked to log in with this account.",
+  "saml_identity_exists_error": "Sorry, the identity returned by your identity provider is already linked with a different Overleaf account.  Please contact your administrator for more information.",
   "saml_invalid_signature_error": "Sorry, the response from your identity provider was signed with an unexpected certificate.  Please contact your administrator for more information.",
   "saml_login_disabled_error": "Sorry, single sign-on login has been disabled for __email__.  Please contact your administrator for more information.",
   "saml_login_failure": "Sorry, there was a problem logging you in.  Please contact your administrator for more information.",