Function encode_utf7_imap 

pub fn encode_utf7_imap(text: String) -> String

Encode UTF-7 IMAP mailbox name

https://datatracker.ietf.org/doc/html/rfc3501#section-5.1.3

Usage:

use utf7_imap::encode_utf7_imap;

let test_string = String::from("Отправленные");
assert_eq!(utf7_imap::encode_utf7_imap(test_string), "&BB4EQgQ,BEAEMAQyBDsENQQ9BD0ESwQ1-");