[ECS] [request]: Support `awslogs-format` option for `logConfiguration.options`

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**Tell us about your request**
Add `awslogs-format` in `logConfiguration.options` of TaskDefinition (ContainerDefinition).

**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?**
Amazon CloudWatch Logs has a feature called EMF which enables the customers to emit a structured log entry and let CWL parse and emit CloudWatch Metrics on behalf of the customers. https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch_Embedded_Metric_Format.html

Recently, Docker merged a new feature to support EMF with `awslogs` logging driver (https://github.com/moby/moby/pull/42838) by using `awslogs-format` option. See also the original issue https://github.com/moby/moby/issues/42731

Now, I think ECS is ready to take this feature and allows the customers to opt-in this feature so that the customers can use EMF feature very easily without any additional infrastructure. They just need to emit the structured json to STDOUT/STDERR!

I couldn't find this option in the ECS doc https://docs.aws.amazon.com/AmazonECS/latest/developerguide/using_awslogs.html#create_awslogs_logdriver_options If you have already supported, please update the document. Otherwise, this request :)

**Are you currently working around this issue?**
Giving up to use EMF and just logging JSON. This is still helpful because CloudWatch Logs Insights can visualize but EMF is preferred to monitor.

**Additional context**
N/A

**Attachments**
N/A

Start by reviewing the ECS TaskDefinition ContainerDefinition logConfiguration options and the linked Docker awslogs-format change. Confirm whether ECS already supports the option; if not, the request is complete when ECS accepts it and the AWS ECS awslogs documentation describes its use.

Written by the indexing model from the issue text.