textproc/py-pycddl: New port: Deserialize CBOR and/or do CDDL schema validation

CDDL is a schema language for the CBOR serialization format. pycddl
allows you to:

• Validate CBOR documents match a particular CDDL schema, based on the Rust cddl library.
• Optionally, decode CBOR documents.

PR: 287129
Approved by: acm (mentor)