including sourcing info in taxon responses

[kueda]

E.g. responses to /v1/taxa/12345 should include

• user who added it
• user who last updated it
• datetime it was added
• datetime it was updated
• name of the provider / source
• link to provider / source

so we can display this on the taxon page. Note that provider stuff are present as columns in the taxa table, while Sources are in another table.

Patrick recommends stuffing these things in the ES index since it doesn't change much and configure ES not to index those attributes, just return them.

Some more notes from Patrick:

what I've tended to do for some user stuff is add a simple representation of the user to the index (just ID and login, usually for search), then use methods like ESModel.fetchBelongsTo to fetch full users from the ES index using the IDs at query time (edited)

it's all a little hacky right now, but generally I try to lookup models once. For example in https://github.com/inaturalist/iNaturalistAPI/blob/master/lib/models/observation.js#L82 it's loading users for many different instances so it all happens in a single query. We're making those User calls anyway for most requests (not sure about taxon show though)