Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- `README.md`:
  Our README.md files are completely different. Discarded upstream changes.
- `app/javascript/core/admin.js`:
  Updating rails-ujs, no real conflict, but a comment to close to changed
  code. Various glitch-soc-only files have been updated to match those changes,
  though.
- `package.json`:
  No real conflict, just an additional dependency in glitch-soc that was too
  close to something updated upstream. Took upstream's changes.

app/javascript/flavours/glitch/packs/public.js

@@ -5,7 +5,7 @@ import loadKeyboardExtensions from 'flavours/glitch/util/load_keyboard_extension
 function main() {
   const IntlMessageFormat = require('intl-messageformat').default;
   const { timeAgoString } = require('flavours/glitch/components/relative_timestamp');
-  const { delegate } = require('rails-ujs');
+  const { delegate } = require('@rails/ujs');
   const emojify = require('flavours/glitch/util/emoji').default;
   const { getLocale } = require('locales');
   const { messages } = getLocale();