Kakfa should support default SSLContext

Currently, to enable SSL in either consumer or producer, we have to provide trustStore file and password. Ideally, if the Kafka server configured with CA signed certificate, since JRE includes certain CA ROOT certs inside "cacerts", Kafka should support SSL without any trustStore file, basically, we should update `org.apache.kafka.common.security.ssl.SslFactory.createSSLContext` to use `SSLContext.getDefault()` when trustStore file is not needed, not sure if there is any other places needs to be updated for this enhancement