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/bytes/copy.ts

@@ -0,0 +1,38 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+/** Copy bytes from the `src` array to the `dst` array. Returns the number of
+ * bytes copied.
+ *
+ * If the `src` array is larger than what the `dst` array can hold, only the
+ * amount of bytes that fit in the `dst` array are copied.
+ *
+ * An offset can be specified as the third argument that begins the copy at
+ * that given index in the `dst` array. The offset defaults to the beginning of
+ * the array.
+ *
+ * ```ts
+ * import { copy } from "https://deno.land/std@$STD_VERSION/bytes/copy.ts";
+ * const src = new Uint8Array([9, 8, 7]);
+ * const dst = new Uint8Array([0, 1, 2, 3, 4, 5]);
+ * console.log(copy(src, dst)); // 3
+ * console.log(dst); // [9, 8, 7, 3, 4, 5]
+ * ```
+ *
+ * ```ts
+ * import { copy } from "https://deno.land/std@$STD_VERSION/bytes/copy.ts";
+ * const src = new Uint8Array([1, 1, 1, 1]);
+ * const dst = new Uint8Array([0, 0, 0, 0]);
+ * console.log(copy(src, dst, 1)); // 3
+ * console.log(dst); // [0, 1, 1, 1]
+ * ```
+ */
+export function copy(src: Uint8Array, dst: Uint8Array, off = 0): number {
+  off = Math.max(0, Math.min(off, dst.byteLength));
+  const dstBytesAvailable = dst.byteLength - off;
+  if (src.byteLength > dstBytesAvailable) {
+    src = src.subarray(0, dstBytesAvailable);
+  }
+  dst.set(src, off);
+  return src.byteLength;
+}