Able to download a single archive file with API by ref name

Problem to solve

Able to download a single file from artifacts using the API by ref

Further details

As discussed in https://gitlab.com/gitlab-org/gitlab-ce/issues/54572#note_120999839 we need a way to download a single file from the artifacts like we used to do in when PAT tokens could be used to access web ui

Proposal

Leverage https://docs.gitlab.com/ee/api/jobs.html#download-a-single-artifact-file but instead of using :job_id we need to use :ref_name similar to download job archive

What does success look like, and how can we measure that?

The exact behavior explained in https://gitlab.com/gitlab-org/gitlab-ce/issues/54572#note_120999839

Links / references

https://gitlab.com/gitlab-org/gitlab-ce/issues/54572#note_120999839