Tests: updated ssl_engine_keys.t test to use SoftHSM v2. Notably, this implies not using slots to identify keys, since "softhsm2-util --init-token" automatically reassigns initialized token to a new slot. Additionally, the "-config" option of is no longer used when generating certificates, as in OpenSSL 1.1.0 and later it conflicts with the configuration file provided via OPENSSL_CONF and results in "conflicting engine id" errors.