When viewing or publishing review requests, we perform a series of

lookups on the file attachments and screenshots (active and inactive) on

the review request and on the draft. This can be up to 8 queries that

we don't really want in most cases (screenshots are never used anymore,

but remain supported for old review requests), but we had no good way of

choosing whether to perform queries for them.
ReviewRequest and ReviewRequestDraft now have new

RelationCounterFields that track how many active and inactive file

attachments and screenshots there are. This allows code to simply check

the populated counters instead of performing a series of queries,

improving performance across the product and all but guaranteeing that

we won't look up screenshots anymore.

Unit tests pass.
Checked existing drafts and review requests and saw that the counters

were populated to the correct values.
Created a new draft and saw that it had the correct counters from the

review request.
Uploaded new file attachments and saw that the draft's counters were

updated correctly.
Deleted a file attachment and saw that the draft's counters were updated

correctly.
Published the draft. Saw that the review request's counters were updated

correctly.