Add command to ontobio that will take input annotations (GAF/GPAD) and outputs TTL

[dougli1sqrd]

Ontobio needs to have a new command specifically to create graph models (TTL) from annotation lines (GPAD/GAF).

(This is what gocamgen does)

• Probably the command will be in validate.py, along side produce.
  • Let's discuss what this should be called.
• There should be a module created where most of the work for this can be made in freedom. (perhaps just rdfgen)
  • the contents of assoc_rdfgen.py, though should be unmoored from this work. We should make this code however we need it to be. assoc_rdfgen.py is under a totally different paradigm.

• validate.py should be the parts that are aware of metadata. But code in rdfgen should know the least about the context. Validate understands the context and then executes into rdfgen correctly, and rdfgen does its job - but shouldn't be very aware. Look to the separation between produce and the parsers: produce knows what the outside world wants, is aware of metadata, etc, but then once we are parsing we have setup the execution environment the way we want and it's on it's way.

[dougli1sqrd]

https://github.com/geneontology/go-ontology/issues/19265