SAML support (#3494)

* PLT-3073: Implement SAML/Okta Server side (EE) (#3422)

* PLT-3137 Support for SAML configuration

* PLT-3410 SAML Database Store

* PLT-3411 CLI to add Identity Provider Certificate and Service Provider Private Key

* PLT-3409 SAML Interface for EE

* PLT-3139 Handle SAML authentication server side

* Add localization messages

* PLT-3443 SAML Obtain SP metadata

* PLT-3142 Login & Switch to/from SAML

* Remove Certs for Database & Clean SAML Request

* Make required Username, FirstName and LastName

* PLT-3140 Add SAML to System Console (#3476)

* PLT-3140 Add SAML to System Console

* Move web_client functions to client.jsx

* Fix issues found by PM

* update package.json mattermost driver

* Fix text messages for SAML

webapp/utils/constants.jsx

@@ -227,6 +227,7 @@ export default {
     GOOGLE_SERVICE: 'google',
     EMAIL_SERVICE: 'email',
     LDAP_SERVICE: 'ldap',
+    SAML_SERVICE: 'saml',
     USERNAME_SERVICE: 'username',
     SIGNIN_CHANGE: 'signin_change',
     PASSWORD_CHANGE: 'password_change',