Convert NPM bundle to ES-Module format

package.json

@@ -2,19 +2,20 @@
   "name": "@novnc/novnc",
   "version": "1.6.0",
   "description": "An HTML5 VNC client",
-  "browser": "lib/rfb",
+  "type": "module",
   "files": [
-    "lib",
+    "core",
+    "vendor",
     "AUTHORS",
     "VERSION",
     "docs/API.md",
     "docs/LIBRARY.md",
     "docs/LICENSE*"
   ],
+  "exports": "./core/rfb.js",
   "scripts": {
     "lint": "eslint app core po/po2js po/xgettext-html tests utils",
-    "test": "karma start karma.conf.js",
-    "prepublish": "node ./utils/convert.js --clean"
+    "test": "karma start karma.conf.cjs"
   },
   "repository": {
     "type": "git",