Add versions.json to Hugo and update references to it.

What does this MR do and why?

This MR just copies over the versions.json file to Hugo project. Currently it is being fetched from gitlab-docs repository. However, to work on port release task automation on this project, we need versions.json to be available locally (specifically for step 3 in the release task).

Screenshots, screen recordings, or links to review app

Versions menu and meta tag should remain the same as before! No changes to logic on versions data.

How to set up and validate locally

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

1. Configure a local GitLab Docs environment: https://gitlab.com/gitlab-org/technical-writing-group/gitlab-docs-hugo/-/blob/main/doc/setup.md.
2. Check versions menu on the header (landing page) - https://new.docs.gitlab.com/review-mr-285/.
3. Check meta tag gitlab_docs_version and make sure it is set to the next release 17.8 - https://new.docs.gitlab.com/review-mr-285/.

Merge request 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 merge request.