Inter-entry reference resolution in client, cli, and archive reader

With #705 (closed) and #706 (closed) and #cross we added cross entry references (both for data and schema, e.g. m_def). Currently, only the processing is resolving these references (via `nomad/datamodel/context.py::ServerContext). Similar implementations are still necessary for:

• client use (e.g. with ArchiveClient)
• command line use (e.g. running parsers with nomad parse)
• when the archive reader is implements the required reference resolution features

Check the metainfo/archive documentation, especially https://nomad-lab.eu/prod/v1/docs/metainfo.html#references-and-proxies to get an idea about the concepts. Check tests/datamodel/test_context.py to get an idea about the implementation.