Epics: https://github.com/elastic/security-team/issues/1974 (internal), #174168
Depends on: #187646

Summary

Create an internal HTTP API endpoint for installing the security_detection_engine Fleet package with prebuilt rules.

• The endpoint should wrap the current server-side logic of installing the latest version of the package.
• We should replace the current client-side logic of installing the latest version of the package via calling the Fleet API directly with a call to our new endpoint.