[Request] Server-side Event Templates

The Agent should be taught how to download `.jfc` event templates from the Cryostat server it's registered with, so that features like the Harvester and Smart Triggers are able to use Custom or Preset Event Templates that are defined on the server and not available locally in the target JVM.

Start by tracing how the Java Agent communicates with its registered Cryostat server and how the Harvester and Smart Triggers currently obtain event templates. Identify the existing local .jfc template loading path and the server interaction entry point. Done means server-defined Custom and Preset Event Templates can be downloaded by the Agent and used by both features.

Written by the indexing model from the issue text.