Show all users with X ability #813
Description
At least as a mod tool (but maybe more broadly; the information isn't secret), it is sometimes useful to be able to ask the question: "who are all the people who can do X?". One simple case is "who are the moderators?" -- that's not clearly exposed anywhere; you have to scan the users page. But "who has curate?" or "who can edit freely?" can also be helpful at times -- as a moderator I want to know if the community can handle those tasks itself or if I need to step in. (Somewhere Else, I was only a community where there were only two non-mod users who could vote to close, which fortunately was obvious.)
One place we could put it (publicly) is on the pages for the individual abilities -- after "what does it do" and "how do I earn it" we could add "who has it already" -- make it a link so we only compute the list on request and not on every visit to the page.