Add --cleanup option to flags script to show groups of flags by status (#31762)

`yarn flags --cleanup` will categorize flags to make it more clear which
ones may need to be cleaned up, experiments checked on, or are blocked
by internal rollouts.

Alternative to #31760

<img width="787" alt="Screenshot 2024-12-13 at 2 31 30 PM"
src="https://github.com/user-attachments/assets/452aee7e-9caf-4210-a621-53941d59cb2b"
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