Add user interview template

We regularly speak with customers to help them solve problems, listen to feedback, and learn more how they use GitLab. These are being documented in many locations and in different formats.

This makes it hard to:

• share feedback with other product managers and engineers
• return to our interview notes if they are scattered over countless Google Docs that are not linked from anywhere shared
• identify trends over multiple interviews if we don't summarize our findings in a timely fashion
• cross-link interviews and meetings to issues, because we don't link to private Google Docs from public issues

The issue template added would be one part of a proposed new process after each meeting:

• create a very brief user interview summary as a confidential issue - one issue per interview
• link to recordings and docs, so that they don't go missing
• share a link to the this issue with your group after every meeting so that developers can keep up to date

I would like to explore automating more of this so that the issue can be created more automatically with links to docs and recordings.