[ECS] [request]: ecs-agent ability to fetch docker logs

**Tell us about your request**
Would be nice to be able to fetch docker container logs by ecs-agent.

**Which service(s) is this request for?**
ECS

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
For those who are not using `awslogs` logging driver, it is impossible to fetch docker container logs without logging into the instance itself. Sometimes for debugging, I need to be able to tail the application logs in real time. Something similar to what `kubectl logs` does.

**Are you currently working around this issue?**
I'm streaming logs to the logs collection software other than CloudWatch Logs, however, it is not real-time, so for some kind of real-time debugging I need tailing logs directly on the instance with `docker logs`

Start by examining the ecs-agent entry points related to Docker containers and log access, then compare their behavior with the Docker logs command. Determine how ECS could expose real-time container log tailing for containers that do not use the awslogs driver. Done means users can fetch and follow those logs without logging into the instance.

Written by the indexing model from the issue text.