(aws-ecs): introduce a deployment lifecycle stage for automatic rollbacks

### Describe the feature

Currently, when using ECS native Blue/Green, Canary, or Linear strategies, deployments flow through well-defined [lifecycle stages](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/blue-green-deployment-how-it-works.html#blue-green-deployment-stages).

However, when an automatic rollback occurs, there isn't an explicit lifecycle stage that corresponds to the rollback event.

### Use Case

I believe many valuable use cases would be unlocked by adding an explicit rollback lifecycle stage. End users would be able to leverage the existing [deployment lifecycle hooks](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/deployment-lifecycle-hooks.html) feature to build workflows that deal with those rollback events, e.g.:
- capture debug data, logs, etc for review
- send notifications to service owners
- etc

### Proposed Solution

_No response_

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### AWS CDK Library version (aws-cdk-lib)

latest

### AWS CDK CLI version

latest

### Environment details (OS name and version, etc.)

all

Start by reading the linked AWS ECS blue/green deployment stages and deployment lifecycle hooks documentation to understand how rollback events fit the existing lifecycle. Then locate the aws-ecs deployment lifecycle implementation and its tests; done means an automatic rollback has an explicit lifecycle stage that can trigger the existing hooks.

Written by the indexing model from the issue text.