Support XEP-0396: Jingle Encrypted Transports - OMEMO (JET-OMEMO)

I apologize if I'm getting the cart before the horse by suggesting this specific enhancement but it would be fabulous to be able to encrypt file transfers in Gajim using OMEMO.

https://xmpp.org/extensions/xep-0396.html states that exploratory implementations are encouraged, but I understand if Gajim wants to wait until XEP-0396 is official. I'm curious though, are there alternative ways to encrypt file transfers until the time in which Gajim users can encrypt them using OMEMO?

Additionally, there are no warnings that files will be sent unencrypted when users have an OMEMO session going with another user and they use the "Send File Directly" to send a file. I tried this method and the file was sent, but luckily this was only a test and it didn't matter if the file was encrypted or not. For people that are using OMEMO to communicate securely, it could cause them a lot of problems if they send a file using Gajim+OMEMO thinking that it will be encrypted and then it gets sent unencrypted.