Create a skeleton shipper executable that:

• Logs to stdout per the control plane pipeline specification.
• Starts a gRPC server when run, that exposes the event gRPC service.
• Can start an HTTP server based on a command line flag that:
  • Exposes the /debug/vars endpoint for metrics (or similar, like the beats /stats endpoint).
  • Exposes the /debug/pprof endpoint for profiling.
• Consumes a configuration file that can configure the gRPC and HTTP interfaces at a minimum. The configuration file will be a subsection of the Elastic agent policy and should use the same format.

Attempt to reuse as much of the agent code as we can for these tasks: elastic/elastic-agent#276