Improve TLS/SSL configuration troubleshooting experience

When encountering TLS/SSL problems with Logstash, it would be very useful if we could provide clearer feedback on errors.

At present, the usual errors are `certificate verify failed` or something like `ssl handshake failure` and none of these are specifically actionable or informative.

I would like Logstash to provide more actionable information when SSL/TLS errors are encountered.