Incorporate a taxon lookup service into our search

[robyngit]

Our best practice recommendation for EML now is to not include the entire hierarchy, and just the leaf taxa (including taxonId), in the record. However, following this recommendation makes data less findable in our current search interface. For example, if a user searches for the order "Primates", they will not see results for datasets that have recorded primates at only the species level in their EML. To resolve this, we could incorporate a taxon lookup services into our search.

@mbjones said:

we've shown how this can work in prototypes with both dynamic lookups to do query expansion, and through graph databases that can do query expansion

See also #2090, Use a taxon database to provide suggested entries in the taxa editor