Heartbeat report TLS details

[urso]

When heartbeat is connecting via TLS, report information on server certificate and connection details if possible:

• TLS version used
• cipher being used
• server certificate expiration date

[andrewkroh]

Also requested on Discuss: https://discuss.elastic.co/t/capture-https-certificate-expiration-dates-using-heartbeat/77865?u=andrewkroh

[RobertoFlores]

There is a date to include this feature on Heartbeat?

[ruflin]

@RobertoFlores There is no specific date.

[elasticmachine]

Pinging @elastic/uptime

[andrewvc]

As an update we now support the expiration dates. I'm on the fence WRT the other info as that crosses into security scanning tools when we're thinking about auditing things like cipher suites and TLS versions.

On the other hand, these are simple tiny fields.

[andrewvc]

I propose we close this for now unless there are any objections. TLS version and cipher suite are usually in the realm of vulnerability scanning tools. I'm not sure they belong in heartbeat.