Give mods an easy way to see how many (valid) flags a user has received

[cellio]

We currently have no aggregation tools for flags. When looking at an account that's engaged in some problematic behavior, it would be helpful to know the history of that behavior. While deleted posts are visible as deleted on the profile (for mods), you can't tell at a glance why they were deleted. Further, if there is a pattern of deleted comments, that's invisible unless you go to the full activity log and look around.

Proposal: on the profile page, change the right-column heading "flags raised" to "flags", change "count" to "number raised", and then for moderators only, add "helpful received" and "all received" with their counts. An initial implementation could just show the numbers, but a full implementation would link to a "flags received" page that is similar to the "flags raised" page (but on the other end).

Let's give moderators better information about patterns of negative behavior to help them do their jobs.

Prompted in part by https://meta.codidact.com/posts/292975.