Added order and direction parameters for sorting admin user pages. This
commit only includes backend api changes.
https://meta.discourse.org/t/make-admin-users-list-sortable-suggestion/47649
Now you can pass in `order` and `asc` parameters to the
`/admin/users/list/<query>.json` endpoint.
Example:
`/admin/users/list/active.json?&order=post_count` which defaults to desc
and
`/admin/users/list/active.json?order=post_count&asc=true`