Merge commit '44cd88adc4e2f4028dcc2b08b98368f0dc90cee4' into glitch-soc/merge-upstream

Conflicts:
- `.github/dependabot.yml`:
  Updated upstream, but we've deleted it.
  Keep it deleted.
- `app/javascript/mastodon/locales/index.js`:
  Reworked upstream, but the code was mostly in
  `app/javascript/locales/index.js` in glitch-soc.
  Updated that file accordingly.
- `app/javascript/packs/public.jsx`:
  Not a real conflict, but different imports in
  glitch-soc and upstream.
- `app/views/layouts/application.html.haml`:
  Conflict due to locales loading and theme system
  discrepancies.
  Updated in our own way.
- `app/views/layouts/embedded.html.haml`:
  Conflict due to locales loading and theme system
  discrepancies.
  Updated in our own way.
- `config/webpack/generateLocalePacks.js`:
  Deleted upstream, as upstream now directly loads the
  JSON at runtime.
  Deleted as well, will switch to runtime loading in
  an upcoming commit.
- `config/webpack/shared.js`:
  Not a real conflict, but different imports in
  glitch-soc and upstream.
- `config/webpack/translationRunner.js`:
  Mostly deleted upstream, to be replaced with `formatjs-formatter.js`
  instead.
  Moved the glitch-soc logic there and deleted the file.

app/javascript/packs/public.jsx

@@ -2,7 +2,7 @@ import './public-path';
 
 import { createRoot }  from 'react-dom/client';
 
-import * as IntlMessageFormat  from 'intl-messageformat';
+import { IntlMessageFormat }  from 'intl-messageformat';
 import { defineMessages } from 'react-intl';
 
 import { delegate }  from '@rails/ujs';
@@ -14,6 +14,7 @@ import { start } from '../mastodon/common';
 import { timeAgoString }  from '../mastodon/components/relative_timestamp';
 import emojify  from '../mastodon/features/emoji/emoji';
 import loadKeyboardExtensions from '../mastodon/load_keyboard_extensions';
+import { loadLocale } from '../mastodon/load_locale';
 import { getLocale }  from '../mastodon/locales';
 import { loadPolyfills } from '../mastodon/polyfills';
 import ready from '../mastodon/ready';
@@ -29,7 +30,7 @@ const messages = defineMessages({
 });
 
 function loaded() {
-  const { localeData } = getLocale();
+  const { messages: localeData } = getLocale();
 
   const scrollToDetailedStatus = () => {
     const history = createBrowserHistory();
@@ -249,6 +250,7 @@ function main() {
 }
 
 loadPolyfills()
+  .then(loadLocale)
   .then(main)
   .then(loadKeyboardExtensions)
   .catch(error => {