Fix some of the Javascript linting issues, as well as bugs and unneeded divergences with upstream (#2208)

* Run eslint --fix

* Fix linting issues in video player and reduce divergences with upstream

This includes a behavior change of not auto-looping videos anymore. I don't
remember loops being ever intended, and they have been removed from upstream
a while ago, but we somehow missed the change.

* Fix lint issues in `app/javascript/flavours/glitch/selectors/index.js`

Those were basically caused by dead code that isn't present upstream, so
that brings us closer to upstream as well.

* Fix linting issue and bug in streaming/index.js

* Fix linting issues in config/webpack/shared.js

* Fix unused import in flavours/glitch/features/ui/index.js

* Fix linting issues and reduce divergences from upstream in flavours/glitch/features/ui/components/video_modal.jsx

* Fix linting issues in flavours/glitch/reducers

* Fix linting issues in glitch-soc onboarding modal

* Fix linting issues in flavours/glitch/features/ui/components/navigation_panel.jsx

* Remove dead code for unused local setting navbar_under

* Fix various linting issues

* Fix linting issues in flavours/glitch/components/scrollable_list.jsx and reduce divergences with upstream

config/webpack/translationRunner.js

@@ -95,7 +95,7 @@ const provideExtractedMessages = () => {
 
   originalExtractedMessages.forEach(file => {
     file.descriptors.forEach(descriptor => {
-      originalKeys.add(descriptor.id)
+      originalKeys.add(descriptor.id);
     });
   });