* Change locales file generation to use JSON sources
Instead of inheriting in JS files, set locale inheritance in the
theme's YML file, and inherit in the generated locale file, rather
than the source file.
* Convert glitch-soc JS translation files to JSON
Obtained running the following:
```sh
sed -i -z "s/import inherited from '.*';\s*\nconst messages = //" *.js
sed -i "s/\s*\/\/.*//" *.js
sed -i -z "s/;\s*export default .*/\n/" *.js
for i in *.js; do
json5 $i | json_pp > ${i}on;
done
```
* Change `yarn manage:translations` to exclude any translation already defined upstream
* Run yarn manage:translations
* Locale script now accepts overrides and new keys from glitch/locales
* Revert glitchsoc changes to mastodon/locales to prevent future merge conflicts
* Only load Intl data for current language
* Extract common chunk only from application.js and public.js
* Generate locale packs, avoid caching on window object
