More clearly indicate what type of endpoint to use

Problem/Motivation

It is not clear how to tell which endpoints are appropriate for use, given that there are (May 23) 1.7 million of them.

Proposed resolution

Clearly indicate what type of endpoint to use, give indications in the UI about it for different use cases.

Remaining tasks

Work out what to do.
Do that.

User interface changes

The Embeddings Model "Endpoint" field gives indications as to what sort of model to use, maybe for different use cases.

API changes

TBD

Data model changes

TBD