feat(puppeteer): export esm modules in package.json (#7964)

* feat(puppeteer): export esm modules in package.json

Signed-off-by: Randolf Jung <jrandolf@chromium.org>

Co-authored-by: Alex Rudenko <OrKoN@users.noreply.github.com>
Co-authored-by: Randolf Jung <jrandolf@chromium.org>

compat/README.md

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+# Compatibility layer
+
+This directory provides an additional compatibility layer between ES modules and CommonJS.
+
+## Why?
+
+Both `./cjs/compat.ts` and `./esm/compat.ts` are written as ES modules, but `./cjs/compat.ts` can additionally use NodeJS CommonJS globals such as `__dirname` and `require` while these are disabled in ES module mode. For more information, see [Differences between ES modules and CommonJS](https://nodejs.org/api/esm.html#differences-between-es-modules-and-commonjs).
+
+## Adding exports
+
+In order to add exports, two things need to be done:
+
+- The exports must be declared in `src/compat.ts`.
+- The exports must be realized in `./cjs/compat.ts` and `./esm/compat.ts`.
+
+In the event `compat.ts` becomes too large, you can place declarations in another file. Just make sure `./cjs`, `./esm`, and `src` have the same structure.

compat/cjs/compat.ts

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+import { dirname } from 'path';
+
+export const puppeteerDirname = dirname(dirname(dirname(__dirname)));

compat/cjs/tsconfig.json

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+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "composite": true,
+    "outDir": "../../lib/cjs/puppeteer",
+    "module": "CommonJS"
+  },
+  "references": [
+    { "path": "../../vendor/tsconfig.cjs.json"}
+  ]
+}

compat/esm/compat.ts

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+import { dirname } from 'path';
+import { fileURLToPath } from 'url';
+
+export const puppeteerDirname = dirname(
+  dirname(dirname(dirname(fileURLToPath(import.meta.url))))
+);

compat/esm/tsconfig.json

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+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "composite": true,
+    "outDir": "../../lib/esm/puppeteer",
+    "module": "esnext"
+  },
+  "references": [{ "path": "../../vendor/tsconfig.esm.json" }]
+}