Create NL search demo

[alexshepard]

Let's build a demo to explore using a model like CLIP to do natural language search on a segment of iNat observations based on what's in the photo.

[alexshepard]

here's a prototype implementation that uses flask, Elasticsearch, and sentence-transformers: https://github.com/alexshepard/inatnls

[alexshepard]

still to be done

• [x] get a version of this demo running somewhere so that the rest of the iNat staff team can play with it