Add service label to container

### Summary
Add `com.amazonaws.ecs.service` label to container of a service

### Description
In order to make it easier to identify containers of service, it would be great to have a label that can easily group them.
This would be useful in EG: cadvisor/other metrics or queries, like an auto NGINX proxy or similar.

Start with issue #523 and confirm how ECS service containers and metadata labels are exposed; the payload names no repository files, tests, or implementation entry point. Done means AWS provides the requested com.amazonaws.ecs.service label on containers belonging to a service and documents its behavior.

Written by the indexing model from the issue text.