Added a very complicated AsyncIterableReader class.

The class was already implemented in
"https://deno.land/std@0.144.0/streams/conversion.ts".  So, I litterally
lost 1 day of work!  I hate myself.

vendor/deno.land/std@0.188.0/_util/os.ts

@@ -0,0 +1,23 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+export type OSType = "windows" | "linux" | "darwin" | "freebsd";
+
+export const osType: OSType = (() => {
+  // deno-lint-ignore no-explicit-any
+  const { Deno } = globalThis as any;
+  if (typeof Deno?.build?.os === "string") {
+    return Deno.build.os;
+  }
+
+  // deno-lint-ignore no-explicit-any
+  const { navigator } = globalThis as any;
+  if (navigator?.appVersion?.includes?.("Win")) {
+    return "windows";
+  }
+
+  return "linux";
+})();
+
+export const isWindows = osType === "windows";
+export const isLinux = osType === "linux";