Show Tagger on the tag view page

Problem to solve

A git tag has a tagger entity, like a commit author in terms of data, but the difference is that one user could have created the last commit, while another user could've tagged that commit (or other object).

Intended users

Anyone that views a tag could see how performed the tagging.

Further details

Gitaly already exposes this data: https://gitlab.com/gitlab-org/gitaly-proto/blob/ab7278ae98f77f1a5fb65b3890a039a022b65893/shared.proto#L90, I think on the front end we could reuse the Git Author widget/logic to show this data.

One thing to note, Git makes it hard, but you could create a tag without a tagger field, so this could be nil.

Proposal

One idea would be to show the avatar, like:

Permissions and Security

This data is already available if you're able to pull the tag, so there shouldn't be an additional security vector here.

Documentation

Shouldn't be required, maybe the updating of one screenshot.

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

GitLab is closer to Git