Map elements of NDPO and PKB class expressions to relevant ontologies

Both NDPO and PKB use class expressions to describe phenotypes using the following ontologies:

• NIF_GrossAnatomy
• NIF_Cell
• SAO
• PATO

For the first 3, we have parallel ontologies in the Monarch import chain.

We could import the NIFSTD ontologies and equivalence axioms to Uberon, CL and GO, we can reason over equivalentClasses, but this would introduce clutter and we would rather avoid this.

We should instead replace URIs with their monarch equivalent URIs in both NDPO.owl and PKB_classes.owl

This should be straightforward for GA and SAO as the existing equivalence axioms here are good, and the OBO ontologies are complete.

For NIF_Cell, no one has been maintaining equivalence axioms to CL. This will require some alignment, and addition of terms to CL. The former can be done with Obol, the latter using cl.termgenie.org