[native] Encrypt files during media mission
Summary:
This is final diff that allows sending encrypted messages on native. The shouldEncryptMedia boolean has been introduced as a feature flag. Now it's hardcoded to false, but we want to enable it only for Comm community (ENG-3526) - this will be done in another diff.
The whole function becomes kind of spaghetti - a refactor follow-up wouldn't be a bad idea
Test Plan:
Sending multimedia works as before when the flag is false.
Set it to true, then send both photos and videos. Ensure both work as expected
Reviewers: atul, marcin, ashoat
Reviewed By: atul, ashoat
Subscribers: tomek
Differential Revision: https://phab.comm.dev/D7236