S3 deployment: set objects metadata per suffix

For the S3 deployment module I notice that it's possible to [set object metadata](https://docs.aws.amazon.com/cdk/api/latest/docs/aws-s3-deployment-readme.html#objects-metadata). Is it possible to set different metadata for different suffixes? I.e. set one cache-control header for `/index.html` and set a different one for `/static/image.png`?

Start by locating the S3 deployment module and its existing object-metadata handling. Determine whether the module can express different metadata for /index.html and /static/image.png, then define and verify behavior for suffix-specific metadata; the issue provides no file or test names.

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