Add missing weather status icons and translations

[provokateurin]

Basically replicate the changes of nextcloud/server#48353.

I was actually just going to write a new weather_status API that offloads the icon stuff to the backend because it is annoying to handle in the frontend, but the changes of that PR make it a lot easier for us, so that is not really necessary.

These changes will only be available in 31, so marking as blocked for now (but it doesn't 31 as the lowest version, we just need the sources for the icons).