enhancement(security): Unify the different TLS options (#972)

* Drop unnecessary Result in HttpService result

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Add validate_hostname TLS option to parallel validate_certificate

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Implement Clone for TlsSettings

Since native_tls::Identity doesn't implement Clone, we have to break
down an Identity into its source components and re-build them each time.

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Use TlsSettings in elasticsearch common settings

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Add the standard TLS options to the Sinks documentation class

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Use standard TLS options in TCP sink

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Move creation of a HTTPS client from TlsSettings into utils

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Use standard TLS options in Kafka sink

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Use standard TLS options in http sink

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Add standard TLS options to clickhouse sink

Signed-off-by: Bruce Guenter <bruce@untroubled.org>

* Add standard TLS options to splunk_hec sink

Signed-off-by: Bruce Guenter <bruce@untroubled.org>