Add scigraph clique and candidate clique endpoints to biolink (dupe see #55)

[kshefchek]

Some time ago I added two functions to scigraph:

/dynamic/candidateClique/{id}
Returns ids that are equivalent and potentially equivalent (xrefs)

/dynamic/clique/{id}
Returns the id and all its equivalents

should we add this functionality to biolink? this probably makes sense as a single function with params that specify how strict a user wants - equivalent, exactMatch, narrowMatch, broad, dbxref, proteins for genes, etc

cc @balhoff @mbrush

[kshefchek]

also related #346

[kshefchek]

exact same ticket from 2017 #55