run abstract method
Runs one request and returns the result as JSON-like values.
A request has a method: embedText, embedImage or embedAudio
with its input, or a retriever.* method with the retriever id that
retriever.create returned and the arguments named as in Google's
JavaScript API. Image bytes and audio samples travel as typed data.
Implementation
Future<Object?> run(Map<String, Object?> request);