Find better way to get those 2 values instead of set it via service def.

[pipecd-bot]

https://github.com/pipe-cd/pipe/blob/8808feb81ca5eafb6b84b585fb4701a0dbba5d9b/pkg/app/piped/cloudprovider/ecs/client.go#L149-L152

This was created by todo plugin since "TODO:" was found in 8808feb when #2007 was merged. cc: @khanhtc1202.

[khanhtc1202]

I'm thinking about adding a new configuration field named TaskSetDefinitionFile which points to a file that contains those two fields: NetworkConfiguration and LaunchType. Besides, it's required to have LoadBalancer configuration to enable created Task serves traffic, thinking about adding that LoadBalancer configuration to this TaskSetDefinition too since it will be registered on TaskSet create.

The new .pipe.yaml will be

apiVersion: pipecd.dev/v1beta1
kind: ECSApp
spec:
  input:
    serviceDefinitionFile: path/to/servicedef.yaml
    taskDefinitionFile: path/to/taskdef.yaml
    taskSetDefinitionFile: path/to/taskset.yaml

and the TaskSetDefinition file content will be

launchType: FARGATE
networkConfiguration:
  awsvpcConfiguration:
    assignPublicIp: ENABLED
    subnets:
      - subnet-0285
      - subnet-0e74
loadBalancers:
  - targetGroupArn: xxx   # the production traffic serving target group
    containerName: sample-app
    containerPort: 80