[gemini extensions]: support streaming responses

[cabljac]

[READ] Step 1: Are you in the right place?

Issues filed here should be about a feature request for a specific extension in this repository. To file a feature request that affects multiple extensions or the Firebase Extensions platform, please reach out to
Firebase support directly.

[REQUIRED] Step 2: Extension name

This feature request is for extension: firestore-genai-chatbot, firestore-multimodal-tasks`

What feature would you like to see?

Support streaming for Gemini extensions

How would you use it?

Allow streaming updates to a firestore doc, to provide streamed responses to the app.

Note

• this may not be supported by all SDKs
• It would require some nuanced thought about updates to firestore and the current flow of the extension logic