Add shortcodes for availability and history

What does this MR do and why?

Add shortcodes for product feature availability and history.

Related issue: #11 (closed)

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. Visit the shortcodes demo page to see examples of the new format: http://localhost:1313/shortcodes/#availability-details
3. Try adding availability and history info in the new format to a regular page (e.g, anything in ../gitlab/doc)

Note that bulk-updating the existing availability and history blocks is a separate issue.

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.