Fix message streaming using react-native-community/fetch

[elisealix22]

This PR demonstrates streaming messages in a Conversation. The issue was React Native's fetch implementation doesn't support streaming with body.

Related RN issue and RN feature request to upvote.

The feature request led me to Realm's workaround realm/realm-js#4155 which was extremely helpful as it pointed me to use text type instead of blob in https://github.com/react-native-community/fetch. However, we can't pass the: { reactNative: { textStreaming: true } } to fetch itself like it's recommended since our fetch methods are auto-generated in the https://github.com/xmtp/proto repo. To workaround that, I patched the default type to text instead of blob which I believe should be ok since it appears it can still be overridden in the options.

Here's the motivation behind using text for streaming to begin with: https://github.com/react-native-community/fetch#motivation.

NOTE: This only resolves streaming on iOS. Android streaming is still under investigation.

Relates to: xmtp/xmtp-js#223

Demo

demo_streaming.mov

Testing steps

• Ensure streaming works with a random wallet address
• Re-test sign in and ensure streaming works with my authenticated address
• Stream on iOS
• Stream on Android

[nplasterer]

I tested this on iOS and works great. Down with merging this as is and iterate on Android in a follow up. 👍

[elisealix22]

Updated the description to indicate this only resolves streaming on iOS. Android is still under investigation 👀