Add support for research object crates

[daniel-thom]

Some users want to store provenance information about their simulation input and output data using research object crates. We could do this in torc.

Acceptance criteria:

1. Torc creates an ro-crate table in its database.
2. Torc stores a JSON-LD formatted crate for each input and output file.
3. The feature is optional, disabled by default.
4. There is a torc CLI command that allows users to add their own crates. They might want to do this for software or files not known by torc.

Open questions:

1. How do we handle Hive-partitioned Parquet files? We should have one crate for one directory, not one per file.