User actions logging/info

[Brightside56]

Checklist

• [x] I've searched the issue queue to verify this is not a duplicate feature request.
• [ ] I've pasted the output of kargo version, if applicable.
• [ ] I've pasted logs, if applicable.

Proposed Feature

I would like to be able to see who performed a particular actions using Kargo API, what may be needed to make work transparent or for investigation of incidents

Motivation

Production usage

Suggested Implementation

• Emiting API-server events related to all user actions - to stdout
• Display user-related information in promotion/freight views in UI
• Putting action initiator username to git commit messages

[krancour]

Related to #793, but feels a bit more comprehensive. Closing #793 in favor of this one.

[krancour]

@devholic I think you might be the best to comment on how well this may have been addressed (or not) by your work a few months back...

Is there more to do here?