[FeatureRequest] Option to return ArrayBuffer

[MPThLee]

Since Response.text of fetch is always decoded using UTF-8, I need to change some code for scraping non-unicode site. (Yeah, it still existing...)
I think providing option for it will be nice feature for this library. returning arraybuffer if option is provided. so I can use decode(py) or TextEncoder(js) for decoding characters properly.

CC: https://stackoverflow.com/questions/55282444/javascript-fetch-characters-with-encoding-issues

[aprilahijriyan]

Interesting, to be honest I don't really know much about JS. Maybe you could submit a PR for this?

Thank you.