feat: add new field to feature flag report (#35108)

### Issue # (if applicable)

N/A

### Reason for this change

Add new field to feature flag report for the `cdk flags` CLI tool.

### Describe any new or updated permissions being added

N/A

### Description of how you validated changes

N/A

### Checklist
- [ ] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: vivian12300