feat: Control the allowed login methods via Super Admin (#12892)

- Control the allowed authentication methods for a chatwoot installation
via super admin configs. [SAML, Google Auth etc]
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[Codex
Task](https://chatgpt.com/codex/tasks/task_e_6917d503b6e48326a261672c1de91462)

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Co-authored-by: Pranav <pranav@chatwoot.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/javascript/dashboard/i18n/locale/en/settings.json

@@ -411,6 +411,7 @@
     "TITLE": "Security",
     "DESCRIPTION": "Manage your account security settings.",
     "LINK_TEXT": "Learn more about SAML SSO",
+    "SAML_DISABLED_MESSAGE": "SAML SSO is currently disabled. Please contact your administrator to enable this feature.",
     "SAML": {
       "TITLE": "SAML SSO",
       "NOTE": "Configure SAML single sign-on for your account. Users will authenticate through your identity provider instead of using email/password.",