Add a diagnostics command to s3guard which does whatever we need to diagnose problems for a specific (named) s3a url. This is something which can be attached to bug reports as well as used by developers.
- Properties to log (with provenance attribute, which can track bucket overrides: s3guard metastore setup, autocreate, capacity,....
- table present/absent
- # of keys in DDB table for that bucket?
- any other stats?