Allow readable streams to be uploaded

[tarcisiozf]

• I understand that this repository is auto-generated and my pull request may not be merged

Changes being requested

Right now there is no way to upload files using a read stream unless it's coming from a fs.ReadStream. This forces the user to go through disk first before sending a stream or to reallocate the whole content to send as Buffer.

In my use case I'm handling a audio stream via web API, transforming the webm via stream and, unfortunately, persisting the file before sending.

The fs.ReadStream already extends a stream.Readable so we can do a small extension to the code without needing to change behavior.

For this PR I decided to add support for Readable instead of replacing the existing FsReadStream checks. I also know that the code is unlikely to be merged but it demonstrates a simple solution to it.

[rattrayalex]

I don't believe this would work well with the current OpenAI API, which inspects filenames for media types (eg, you need a .mp3 extension for an audio file to be interpreted as mp3). That's why we only allow fs.createReadStream() to bypass toFile() – it includes a filename.

This may work with node Readable, but would it work with web ReadableStream?

Does this actually make the request as expected with a large file, streaming the request body? I think further changes would be required for that, and we might be best off waiting for #402 to land for that.

[tarcisiozf]

Thanks for the reply, now the API constraints are clear to me. For now I'll use await toFile(buffer, 'audio.webm') instead of a stream solution.

[rattrayalex]

Great. You may want to follow #418 which documents a feature request for this.