Create a ReadableStream<Uint8Array> from a Reader.

When the pull algorithm is called on the stream, a chunk from the reader will be read. When null is returned from the reader, the stream will be closed along with the reader (if it is also a Closer).

An example converting a Deno.FsFile into a readable stream:

import { readableStreamFromReader } from "https://deno.land/std@$STD_VERSION/streams/readable_stream_from_reader.ts";

const file = await Deno.open("./file.txt", { read: true });
const fileStream = readableStreamFromReader(file);