Support queries over a single document in odinson's API

[hillelt]

When developing an extractor for a relation, analysts often write patterns to match specific example sentences they've gathered in advance. To allow quick feedback, it would be nice if Odinson had the ability to run a pattern against a specific sentence or document, in their raw text form.

A possible solution would be to add an API call which takes as input a query and a text document, indexes the doc in-mem and runs the query against the in-mem index.

[BeckySharp]

FWIW that's what I do in the OdinsonWebapp -- using an in-mem index