Current WIP to enable TLS on https://github.com/kamailio/kamailio/pull/3734.
Use existing `opt_ssl_mode` and map as follows.:
1. 0(off), 1(SSL_MODE_DISABLED): mariadb-connector-c defaults 2. 2(SSL_MODE_PREFERRED) 3(SSL_MODE_REQUIRED) 4(SSL_MODE_VERIFY_CA): `MYSQL_OPT_SSL_ENFORCE` 3. 5(SSL_MODE_VERIFY_IDENTITY): `MYSQL_OTP_SSL_VERIFY_SERVER_CERT`