[ECS] [request]: provide more details of what is happening in the different task states

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**Tell us about your request**
What do you want us to build?
It will be useful if ECS can provide more details of what is happening while the task is in the different states [1]. Therefore if it fails for example in the provisioning state it will provide more details of why it fails.

[1] https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-lifecycle.html
**Which service(s) is this request for?**
Fargate, ECS

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
I got a task that was stuck in provisioning state but not clear message about the error was provided. We found it was an issue related with the Capacity Provider but it will be nice if ECS can provide a clear message about what it was stuck in Provisioning state.

Start by reading the linked ECS task lifecycle documentation and the request's Fargate/ECS context. The issue does not name repository files, tests, or implementation entry points; done would mean ECS exposes clear explanations for what is happening in each task state, especially failures while provisioning.

Written by the indexing model from the issue text.