Draft: 2.84.0

Untested, but should be functionally equivalent to 2.83.5 (translation updates and minor changes in tests only).

I'm not testing or uploading this right now, I'm not sure whether it would be better to let 2.83.5 migrate (it's blocked by glibc) or proceed directly to 2.84.0 (resetting the glib2.0 migration timer). @jbicha, any opinion?