Add element classes used in ee branch qa-257-group-saml-sso
What does this MR do?
Adds classes to elements used in ee branch https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7479
What are the relevant issue numbers?
Does this MR meet the acceptance criteria?
Changelog entry added, if necessary
Tests added for this feature/bug
- Conforms to the code review guidelines
Conforms to the [merge request performance guidelines](https://docs.gitlab.com/ee/development/merge_request_performance_guidelines.html)
- Conforms to the style guides
Conforms to the database guides