build: use mjs files for ng-dev configuration

In preperation for ng-dev requiring mjs files for configuration, switch over our usage

.ng-dev/commit-message.mjs

@@ -0,0 +1,38 @@
+/**
+ * The configuration for `ng-dev commit-message` commands.
+ *
+ * @type { import("@angular/ng-dev").CommitMessageConfig }
+ */
+export const commitMessage = {
+  maxLineLength: Infinity,
+  minBodyLength: 20,
+  minBodyLengthTypeExcludes: ['docs'],
+  // If you update this, also update the docs.
+  // https://github.com/angular/angular/blob/main/contributing-docs/commit-message-guidelines.md#scope
+  scopes: [
+    'animations',
+    'benchpress',
+    'common',
+    'compiler',
+    'compiler-cli',
+    'core',
+    'dev-infra',
+    'devtools',
+    'docs-infra',
+    'elements',
+    'forms',
+    'http',
+    'language-service',
+    'language-server',
+    'localize',
+    'migrations',
+    'platform-browser',
+    'platform-browser-dynamic',
+    'platform-server',
+    'router',
+    'service-worker',
+    'upgrade',
+    'vscode-extension',
+    'zone.js',
+  ],
+};