added user activity filtering
What does this MR do?
This merge request add User Activity filtering, per #26700.
Are there points in the code the reviewer needs to double check?
Why was this MR needed?
It brings feature parity with the other activity streams found through GitLab, such as Project Activity and Group Activity.
Screenshots (if relevant)
Does this MR meet the acceptance criteria?
- Changelog entry added
- Documentation created/updated
- API support added
- Added for this feature/bug
- All builds are passing
- Conform by the merge request performance guides
- Conform by the style guides
Branch has no merge conflicts with
master(if it does - rebase it please)
- Squashed related commits together
What are the relevant issue numbers?