Add textStream() to interfaces that represent a byte stream (request, response, blob). This is equivalent to piping the byte stream through a TextDecoderStream(), and reduces this small piece of broilerplate for commoncases.
A small ergonomic change to make it easier to stream text from a byte stream such as response (or blob) to a sink that accepts strings. Helps with a footgun of forgetting to pipe through a TextDecoderStream.
Explainers: https://github.com/whatwg/fetch/pull/1862