SSL: Need support for limiting TLS versions

[seang-es]

We've been getting requests to limit the TLS versions supported by Kibana in order to satisfy customer security requirements. Similar to Shield's shield.ssl.supported_protocols, they need to be able to exclude older versions of TLS.

This may be limited by the version of node.js in use.

[epixa]

Even though this came first, I'm going to close this ticket in favor of the broader plan for ssl configuration, which will cover this particular issue as well: #7777