Add Elastic Cloud Sample

[KodrAus]

Add a sample that connects to an Elastic Cloud cluster with TLS and user credentials. These can be passed to the sample as command line args so nothing needs to be persisted anywhere.

If no args are passed maybe it could try read the parameters from environment variables so live demos don't need to display anything.

[KodrAus]

It would also be good to update the benches to support queries to Elastic Cloud. I'd expect this to just about wipe out any differences between the clients but it'd be good to measure more realistic connections.