Include .mjs files.

Author: iclanton

libraries/rush-sdk/config/typescript.json

@@ -0,0 +1,9 @@
+/**
+ * Configures the TypeScript plugin for Heft.  This plugin also manages linting.
+ */
+{
+  "$schema": "https://developer.microsoft.com/json-schemas/heft/typescript.schema.json",
+  "extends": "@rushstack/heft-node-rig/profiles/default/config/typescript.json",
+
+  "emitMjsExtensionForESModule": true
+}

libraries/rush-sdk/package.json

@@ -9,6 +9,7 @@
   },
   "homepage": "https://rushjs.io",
   "main": "lib/index.js",
+  "module": "lib/index.mjs",
   "typings": "dist/rush-lib.d.ts",
   "scripts": {
     "build": "heft build --clean",