since we don't have a hard date for this, and I've already made one wrong educated guess, I'd rather not have another massive outage.
A security update will have to be made to remove the old key as soon as the new one is rolled. This is not ideal, but it's the least disruptive option.
this allows localizing disconnection screens (at least, once #4512 has been addressed) and the disconnect reasons shown on the console.
We already had disconnect messages implicitly localized in a few places, so this is just formalizing it.
This does break BC with any code that previously passed translation keys as the disconnect screen message, because they'll no longer be translated (only Translatables will be translatated now).
I previously avoided this due to being unsure of the effects; however, it's clear that we already use typed properties on Threaded things in other places anyway, and the only known issues are with uninit properties, and arrays.
This brings a significant performance improvement to login sequence handling, reducing CPU cost of `PrepareEncryptionTask` by over 90% and `ProcessLoginTask` by over 60%. It also allows us to shed a dependency.
