Update ECS module to enable Dynamic Port Mapping

[mswezey23]

Currently, as provided, one cannot do rolling deployments on the ECS-EC2 module.

This is due to the hostPort being configured (port 80) and not allowing AWS/Docker magic to occur.

The fix is simple. Update hostPort: 0 instead of hostPort: 80 on both task definitions.

Doing this one update allowed for a smooth rolling update to occur.
Verified by monitoring the ECS Cluster -> Services -> Event logs and checking which task definitions were active.

Example Error:

service [alpha-retool-main-service](https://us-east-1.console.aws.amazon.com/ecs/home?region=us-east-1#/clusters/alpha-retool-ecs/services/alpha-retool-main-service) 
was unable to place a task because no container instance met all of its requirements. 
The closest matching container-instance is already using a port required by your task. For more information, see the [Troubleshooting section]
(http://docs.aws.amazon.com/AmazonECS/latest/developerguide/troubleshooting.html).

[mswezey23]

You will also need to update SG ingress rules for the EC2 instance(s) to allowed the ALB traffic to occur over the ephemeral port range.

With this, you can delete the the Port 80 & 443 ingress rules for the EC2 instance. ALB should receive incoming HTTP(S) traffic and manage the SSL connection via ACM certs.

ingress {
    description     = "Ephemeral Port Range DPM"
    from_port       = "49153"
    to_port         = "65535"
    protocol        = "tcp"
    security_groups = [aws_security_group.alb.id]
  }

Sauce: https://docs.aws.amazon.com/AmazonECS/latest/APIReference/API_PortMapping.html