fix: forcibly take control of i18n singleton language

[amcgee]

There's yet another race condition in our handling of i18n - in this case, any component that uses d2-i18n-generate will inject a i18n.setLanguage('en') which is loaded whenever that component is required (with dynamic imports this can be after initial page load!)

This "works around" this issue by always listening for i18n's languageChanged event and immediately resetting the language if it was "hijacked" out from under us - for instance if some component (cough Headerbar) ALSO has logic to set the locale when the user is logged in (which doesn't even work, different issue...) or worse tries to set it to something incorrect (like English)

There's still an issue here, since once the language is set (i.e. english on load in the headerbar) the strings won't be updated until that component re-renders - we may need to force a full-page rerender whenever the language changes, at least until we can make i18n react-aware, but that's an issue for another day.

Now the Login dialog in platform apps should always correctly adopt the browser locale, and the app should be correctly translated to the logged-in user's locale, but the headerbar will still appear in English.

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[varl]

Not ideal, we need to figure out a way to "solve" i18n for our use case.

[stale]

Hi! Due to a lack of activity on this issue over time it seems to be stale. If still relevant, please provide information that moves it forward: e.g. more information, reason to keep it open, supply a pull request, etc.
Any activity will keep it open, otherwise it will be closed automatically. Thanks! 🤖

[stale]

Automatically closing due to lack of activity. 🤖