Don't expose the demo by default

Make rollup bundle the demo app by default and let the index.js point to
the actual implementation.

This way we can use the default entry point of the package when including it
in other packages and don't have to reference specific files.

packages/auth/demo.js

+import './index';
+import './vpu-auth-demo';

packages/auth/index.js

 import './vpu-auth';
-import './vpu-auth-demo';

packages/auth/rollup.config.js

@@ -11,7 +11,7 @@ const build = (typeof process.env.BUILD !== 'undefined') ? process.env.BUILD : '
 console.log("build: " + build);
 
 export default {
-    input: 'index.js',
+    input: 'demo.js',
     output: {
         file: 'dist/bundle.js',
         format: 'esm'