Make a bio profile for SSSOM

[kevinschaper]

I had the thought that for gene mapping sets it might be nice to be able to easily subset by taxon, and asked about potentially adding subject_taxon and object_taxon. @cmungall suggested that for something subject matter specific like that, it might make sense to make a bio profile for SSSOM.

[matentzn]

Thank you @kevinschaper

this related a bit to mapping-commons/semantic-mapping-vocabulary#3 and the unspoken question whether SKOS should be used for cross species mappings or not. In any case, lets collect some more useful elements for a potential bio-focused profile of SSSOM and see if it is worth implementing. In the absence, we should reconsider making a push on #149 which would allows adding custom columns regardless of whether they are in any official profile or not..