Support multiple formats in the same run

[bentsherman]

Proposed syntax:

prov {
  formats {
    legacy {
      file = 'manifest.json'
      overwrite = true
    }
    bco {
      file = 'bco.json'
      overwrite = true
      // could put extra bco-specific fields here, etc
    }
  }
  // ...
}

[simleo]

For Workflow Run RO-Crate the output is actually a directory. It could be output as a zip archive though.

[bentsherman]

This is another reason why I want to have separate config for each format, since not every format is guaranteed to output a single file. So an RO-crate for example could have a directory setting instead of file.