search: send dynamic filters in stream api
Created by: keegancsmith
This is a proposed API for sending dynamic filters via the streaming API. It only implements the backend portion, by converting the graphql types at the end of the stream into the stream type.
The proposed API is exactly the same as our graphql type. I'm unsure if we can make this smaller at all, nor if it is worth doing it since this list is usually small.
Part of #13067 (closed)