watch a bucket for new keys.

It splits by keys by the last 24 1hr time periods, and list keys, if it finds new ones it pushs them to the stream.


- [x] List keys in an s3 bucket
- [ ] paging, if it returns more results then it can list, it should continue
- [ ] eval if this is a good use of streams (maybe...)
- [ ] move list of seen keys out of memory (it will be too big, it needs to serve restart)