Add filtering by attention requests
I added the attention-requests docs in !81250 (merged) but had to redact the portion about filters because I wasn't sure how I wanted to do it. This merge request gardens in attention requests to the ways that users can filter merge requests.
Related issues and merge requests
- Related to !81250 (merged) where I added the rest of the docs
- Related to #353235 (closed)
- Related to #356694 (closed)