Allow SpanQuestion in ChatField

[keithporcaro]

It would be very helpful if SpanQuestions could be used for ChatFields.

We’re currently using Argilla to audit a conversational chatbot. In this case, the user may ask multiple questions in an interaction, so we can’t simply use a pair of text fields. And there are several cases where we need span highlighting (to identify wrong answers, PII, etc.)

Currently, if a SpanQuestion is attached to a ChatField, the ChatField UI simply won’t appear in the annotation—users see the raw dictionary instead.

Our current workaround is to parse the chat conversation into a markdown text field, but that has obvious downsides, including more effort to parse the subsequent results.