[Feature request] Create a client method to check remote availability in Workplace search

In Logstash's Enterprise Search plugin, for the Workplace output we use a method to check the connections to the remote:
https://github.com/logstash-plugins/logstash-integration-elastic_enterprise_search/blob/8ff2f8fc982f8036772430c670d1717895333a97/lib/logstash/outputs/elastic_workplace_search.rb#L103-L105

With version `8.0` of Workplace search the underlying http endpoint has been removed, made some test to fail as described in https://github.com/logstash-plugins/logstash-integration-elastic_enterprise_search/issues/14.

The solution could be to use other methods, that implicitly prove the connectivity.

The Workplace client should provide an explicit API to check the connectivity, so that's future proof.
Elasticserach Ruby client provide a similar feature, as reference: https://www.rubydoc.info/gems/elasticsearch-api/Elasticsearch/API/Actions#ping-instance_method