* domain cookie fix:
- don't set cookies for service worker modifiers if response is not 200
- don't add existing cookies to Cookie or Set-Cookie headers
- add sw_/, wkrf_/ modifiers to generate paths
- enable domain cookie cacheing by default with fakeredis for live index and record mode, keyed by collection
- reqs: add fakeredis, tldextract, update warcio
- tests: add initial tests for domain cookie rewriting