[Entity Analytics] Make risk engine APIs public

[hop-dev]

In v9 internal APIs will not be able to be called other than from Kibana itsself, we have found the risk engine init and status APIs useful for diagnosing and solving SDHs we should make public versions of them and then eventually delete the internal ones, the same way we have with asset criticality APIs.

[elasticmachine]

Pinging @elastic/security-entity-analytics (Team:Entity Analytics)

[jaredburgettelastic]

Closing in favor of duplicate (private) issue here: https://github.com/elastic/security-team/issues/11164