Translate graph output to Phenopackets

[caufieldjh]

Describe the desired behavior

This is specifically relevant to KG-COVID-19 and its newer clinical data additions, but potentially to any KG containing representations of clinical observations.
We would like to be able to produce Phenopackets from the graph nodes/edges.
Since the KGs contain all data in just two files rather than spread out amongst a bunch of tables, this is an excellent opportunity to parse those files directly to a standard set of schema.

Additional context

See https://phenopacket-schema.readthedocs.io/en/latest/
and
https://github.com/phenopackets/phenopacket-schema