Use EntityRefs for Group ID and Rule ID

Created by: MegaphoneJon

It will give a much better end-user experience if users can select dedupe rules and groups from a list, rather than typing in their IDs. Fortunately, there's a helper function to handle this: https://docs.civicrm.org/dev/en/latest/framework/quickform/entityref/#js-add-from-client-side

Again, I'm happy to submit the PR but the others need to be merged first to avoid merge conflicts.