Handle language pack uninstallation (#171891)

The most important part of this change is that we now listen for when extensions are uninstalled and if they uninstalled language currently set then a modal will show up prompting for restart (required to change the language back to English).

This change also makes the LocaleService the thing that writes to the argv.json instead of a few places doing it

and cleans up some of the wording.

Fixes #82791