Add ECS task internet exposure analysis

[kunaals]

Summary

• mark ECS tasks internet exposed when their host EC2 instance is exposed
• run new analysis job automatically
• document exposed_internet for ECSTask

Testing

• make test_lint
• make test_unit
• make test_integration (fails: Couldn't connect to localhost:7687)

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https://chatgpt.com/codex/tasks/task_b_685091dd27048323bdbf6656b9790771