Part of the code such as #show_path is already present on the presenter.
Also avoid having code in two places (helper and presenter)

Sanitize and assert html_safe. Additional layer of defense - on top of
GitLab already requiring group names to be composed of small set of
chars A-Z, - and spaces.

Only link to cluster if user can read cluster

Make clear that arg is a GroupClusterablePresenter

Add more specs for completeness