[ECS] [request]: Filter task by task group in ListTask API

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**Tell us about your request**
What do you want us to build?
The ECS API call ListTask[1] allow to filter tasks by family , container instance , and desired status, but not for task group. It will be good if a filter by task group could be added.

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

**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?**
If you run the tasks grouping tasks by task group, you will need to monitoring and query the task that were running in this group.

**Are you currently working around this issue?**
Currently it is necessary to list all tasks and then manually apply a filter to get the tasks of a specific task group.

**Additional context**
Anything else we should know?

**Attachments**
If you think you might have additional information that you'd like to include via an attachment, please do - we'll take a look. (Remember to remove any personally-identifiable information.)

Start with the AWS ECS ListTasks API reference linked in the issue and review its existing filtering options and task-group behavior. Done would mean ECS supports querying ListTask results by task group, with the behavior documented in that API reference.

Written by the indexing model from the issue text.