Adds noopener noreferrer to target="_blank" links

What does this MR do and why?

Adds rel="noopener noreferrer" to links with <a target="_blank" in multiple different places.

This is a best practice to avoid "Reverse Tabnapping".

Screenshots or screen recordings

This was surfaced by running an authenticated DAST active scan on a self-managed GitLab instance.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.