WIP: Load settings into consul cluster with `gitlab-ctl upload-settings`

What does this MR do?

Towards #3002 (closed) we add a tool to take a user-supplied settings file, and add it to the gitlab-ctl command line.

Checklist

See Definition of done.

• Change added to CHANGELOG.md. Not applicable for Documentation changes and minor changes.
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA, if applicable
• MR targeting master branch
• MR has a green pipeline on GitLab.com

Reviewer Checklist

In addition to above, reviewer must:

• Pipeline is green on dev.gitlab.org if the change is not touching documentation or internal cookbooks

References

#3002 (closed)