Use an edit tag instead of appending AFCH to edit summaries

[NovemLinguae]

An edit tag ( https://en.wikipedia.org/wiki/Special:Tags, https://www.mediawiki.org/wiki/Help:Tags ) would help speed up Quarry SQL queries when we need to do things like figure out a user's AFC accept count.

Current:

Proposed:

Related: https://en.wikipedia.org/wiki/Wikipedia:Request_a_query#AfC_review's_25th_review

[primefac]

Huh... I thought we had turned it into a tag ages ago...

[NovemLinguae]

Another possible use case: detecting edit conflicts between AFCH users, while ignoring edit conflicts that aren't with AFCH users. The API query would be something like action=query&prop=revisions&rvtag=AFCH