wip: Update jpeg decoder.

I was trying to see an xray that I got recently (happy to email it
privately if it helps), which fails to decode on the demo with:

```
JPX Error: Unsupported COD options (selectiveArithmeticCodingBypass) jpx.js:339:23
```

So this tries to update to openjpeg via
mozilla/pdf.js#17946, which should support it.
However:

 * It's very WIP (the image decodes correctly on the worker, but I only
   see black on the canvas, however I see correct metadata).
 * I haven't updated all the references to the other decoders.
 * It loads the non-jpeg decoders as a module which I can't test, but
   probably breaks them. I also need to update the sync decoders, which
   likely doesn't work.

I don't think I'll have time to finish this, but posting it here in case
it saves someone time or someone has the time to finish it up.

Thanks.

decoders/pdfjs/decode-jpeg2000.js

@@ -4,15 +4,65 @@
 // Do not warn if these variables were not defined before.
 /* global importScripts, JpxImage */
 
-importScripts('jpx.js', 'util.js', 'arithmetic_decoder.js');
+import OpenJPEG from "./openjpeg.js";
 
-self.addEventListener('message', function (event) {
+class JpxError extends Error {
+  constructor(msg) {
+    super(`JPX error: ${msg}`, "JpxError");
+  }
+}
+
+class JpxImage {
+  static #module = null;
+
+  static decode(data, ignoreColorSpace) {
+    this.#module ||= OpenJPEG();
+    const imageData = this.#module.decode(data, ignoreColorSpace);
+    if (!imageData) {
+      throw new JpxError("JPX decode failed");
+    }
+    return imageData;
+  }
+
+  static cleanup() {
+    this.#module = null;
+  }
 
+  static parseImageProperties(stream) {
+    // No need to use OpenJPEG here since we're only getting very basic
+    // information which are located in the first bytes of the file.
+    let newByte = stream.getByte();
+    while (newByte >= 0) {
+      const oldByte = newByte;
+      newByte = stream.getByte();
+      const code = (oldByte << 8) | newByte;
+      // Image and tile size (SIZ)
+      if (code === 0xff51) {
+        stream.skip(4);
+        const Xsiz = stream.getInt32() >>> 0; // Byte 4
+        const Ysiz = stream.getInt32() >>> 0; // Byte 8
+        const XOsiz = stream.getInt32() >>> 0; // Byte 12
+        const YOsiz = stream.getInt32() >>> 0; // Byte 16
+        stream.skip(16);
+        const Csiz = stream.getUint16(); // Byte 36
+        return {
+          width: Xsiz - XOsiz,
+          height: Ysiz - YOsiz,
+          // Results are always returned as `Uint8ClampedArray`s.
+          bitsPerComponent: 8,
+          componentsCount: Csiz,
+        };
+      }
+    }
+    throw new JpxError("No size marker found in JPX stream");
+  }
+}
+
+console.log(JpxImage);
+
+self.addEventListener('message', function (event) {
   // decode DICOM buffer
-  var decoder = new JpxImage();
-  decoder.parse(event.data.buffer);
+  let res = JpxImage.decode(event.data.buffer, /* ignoreColorSpace = */ true);
   // post decoded data
-  var res = decoder.tiles[0].items;
   self.postMessage([res]);
-
 }, false);