Update the webpack example to account for outputting of JavaScript modules (PR 17055 follow-up)

*Please note:* While following the steps in the README still works with this patch, in the sense that the example runs and successfully renders a PDF document, I unfortunately cannot tell if it illustrates Webpack best practices.

src/pdf.worker.entry.js

@@ -1,21 +0,0 @@
-/* Copyright 2022 Mozilla Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-/* globals require:readonly */
-/* eslint-disable import/no-commonjs */
-
-(typeof window !== "undefined"
-  ? window
-  : {}
-).pdfjsWorker = require("./pdf.worker.mjs");