Fix `/share` and cleanup and reorganize frontend locale loading (#25240)

.prettierignore

app/helpers/react_component_helper.rb

app/javascript/mastodon/actions/streaming.js

app/javascript/mastodon/containers/admin_component.jsx

app/javascript/mastodon/containers/compose_container.jsx

app/javascript/mastodon/containers/mastodon.jsx

app/javascript/mastodon/containers/media_container.jsx

app/javascript/mastodon/load_locale.js

app/javascript/mastodon/locales/global_locale.ts

app/javascript/mastodon/locales/index.js

app/javascript/mastodon/locales/index.ts

app/javascript/mastodon/locales/intl_provider.tsx

app/javascript/mastodon/locales/load_locale.ts

app/javascript/mastodon/locales/locale-data/README.md

app/javascript/mastodon/locales/locale-data/co.js

app/javascript/mastodon/locales/locale-data/oc.js

app/javascript/mastodon/locales/locale-data/sa.js

app/javascript/packs/admin.jsx

app/javascript/packs/application.js

app/javascript/packs/public.jsx