To perform various configuration operations on SSL_CTX, OpenSSL provides
SSL_CONF_cmd(). Specifically, to configure ciphers for a listener,
"CipherString" and "Ciphersuites" file commands are used:
https://www.openssl.org/docs/man1.1.1/man3/SSL_CONF_cmd.html
This feature can be configured in the "tls/conf_commands" section.