feat: web client refresh (#1476)

Give the web client a major overhaul.

User-visible highlights include:

* Mobile is now fully supported.
* Added fullscreen support on mobile.
* Better support for dark mode.
* Added mime icons to the torrent list.
* Improved theme consistency across the app.

Maintainer highlights include:

* Updated code to use ES6 APIs.
* No longer uses jQuery UI.
* No longer uses jQuery.
* Use Webpack to bundle the Javascript, CSS, and assets together -- the entire bundle size is now 68K gzipped.
* Added eslint / prettier / stylelint tooling.
* Uses torrent-get's 'table' mode for more efficient RPC calls.

code_style.sh

@@ -62,7 +62,10 @@ fi
 cd "${root}/web" || exit 1
 if [ -n "$fix" ]; then
   cd "${root}/web" && yarn --silent install && yarn --silent 'lint:fix'
-elif ! yarn -s install && yarn --silent lint; then
+elif ! yarn -s install; then
+  echo 'JS code could not be checked -- "yarn install" failed'
+  exitcode=1
+elif ! yarn --silent lint; then
   echo 'JS code needs formatting'
   exitcode=1
 fi