Use webpack to create a CommonJS module from micromark's ESM implementation, convert to using that.

micromark/package.json

@@ -2,7 +2,8 @@
   "name": "markdownlint-micromark",
   "version": "0.1.0",
   "description": "A trivial package that re-exports some micromark functionality as a CommonJS module",
-  "exports": "./exports.mjs",
+  "type": "commonjs",
+  "exports": "./micromark.js",
   "author": "David Anson (https://dlaa.me/)",
   "license": "MIT",
   "homepage": "https://github.com/DavidAnson/markdownlint",
@@ -11,10 +12,17 @@
     "url": "https://github.com/DavidAnson/markdownlint.git"
   },
   "bugs": "https://github.com/DavidAnson/markdownlint/issues",
+  "scripts": {
+    "build": "webpack --no-stats"
+  },
   "engines": {
     "node": ">=14.18.0"
   },
   "dependencies": {
     "micromark": "3.1.0"
+  },
+  "devDependencies": {
+    "webpack": "5.75.0",
+    "webpack-cli": "5.0.1"
   }
 }