Ubiquiti removed keytool (and java) from recent releases of Unifi OS. This moves from keytool to openssl's native pkcs12.
Tested on Unifi Dream Machine which runs Unifi OS and a built-in Unifi controller.
Also added backup of existing files prior to change in case anything goes wrong, and update system configuration with compatible ciphers.
Clear OTP secret if environment variable is set to empty. This is for when the 2FA is disabled.
Rename `_is_idn` function to `_is_idn_cyon`.
Remove usage of curl (except for URL encoding of data).
Instead of cleaning up the cookie jar, get rid of it completely and logout of cyon instead.