campaigns: implement preview UI filtering dropdowns

Created by: LawnGnome

This PR implements filtering dropdowns on the campaign preview page that allow filtering based on the current state of the changeset, and the actions to be performed on the changeset.

Implementation wise, the most interesting aspect is that the action filtering has to be done in the resolver, rather than in the query, since we don't have the actions until the dry run of the reconciler has occurred. Since this adds another place where we have to paginate the results, the resolver tests are fairly heavy here.

Closes #16960 (closed).