dillon1000/react

Allow the streaming config to decide how to precompute or compute chunks (#21008)

Some legacy environments can not encode non-strings. Those would specify
both as strings. They'll throw for binary data.

Some environments have to encode strings (like web streams). Those would
encode both as uint8array.

Some environments (like Node) can do either. It can be beneficial to leave
things as strings in case the native stream can do something smart with it.