Make the correlation packages public

I’d like to start a discussion about moving the gitlab.com/gitlab-org/gitlab-workhorse/internal/correlation package out of workhorse/internal since I’d like to share it Gitaly. I discussed this with @jacobvosmaer already but @nick.thomas was away at the time and Jacob (rightly) wanted Nick to be part of the convo…

The three options are:

1. Duplicate the code in Gitaly (and possibly also Pages and other Go services)
2. Move it to a public package on workhorse, eg gitlab.com/gitlab-org/gitlab-workhorse/correlation
3. Move it to a new project….. (edited)

Right now, I’m thinking 3, but also okay-ish with 2.

Slack conversation: https://gitlab.slack.com/archives/C2TDMHW69/p1542199163080700