Support for custom Ansible tasks

What does this MR do?

Add support for custom Ansible tasks in the common role for Omnibus nodes. To allow GitLab Version Exporter work a custom deb package was needed so custom package support was added as well.

Also adding custom uninstall tasks, so that customisations added by the custom install tasks can be removed during the uninstall.

Related issues

Closes #369 (closed)

Author's checklist

When ready for review, the Author applies the workflowready for review label and mention @gl-quality/get-maintainers:

• Merge request:
  • Corresponding Issue raised and reviewed by the GET maintainers team.
  • Merge Request Title and Description are up to date, accurate, and descriptive
  • MR targeting the appropriate branch
  • MR has a green pipeline
• Code:
  • Check the area changed works as expected. Consider testing it in different environment sizes (1k,3k,10k,etc.).
    • Tested against Staging Ref using https://gitlab.com/gitlab-org/quality/gitlab-environment-toolkit-configs/staging-ref/-/merge_requests/56
  • Documentation created/updated in the same MR.
  • If this MR adds an optional configuration - check that all permutations continue to work.