* sw: instead of rebuilding sw.js with slightly different settings (baked in index.html + ruffle.js cache),
can now just use the published sw.js release with custom queryArgs, injectScripts=ruffle/ruffle.js
index.html is cached automatically on-load
webpack: for dev server, still build 'sw.js' locally to allow dynamic updates when developing on a linked wabac.js
remove src/sw.js, as no longer used, just importing from wabac.js directly
bump to 1.8.9