[Auth] Fix compat demo which was missing index.html file (#5561)

* Fix up auth-compat demo

* Index file

Author: sam-gc

packages/auth-compat/demo/.gitignore

@@ -3,4 +3,3 @@ src/config.js
 public/config.js
 public/service-worker.*
 public/web-worker.*
-public/index.*

packages/auth-compat/demo/package.json

@@ -26,11 +26,11 @@
   },
   "license": "Apache-2.0",
   "devDependencies": {
-    "rollup": "2.57.0",
-    "@rollup/plugin-json": "4.1.0",
-    "rollup-plugin-replace": "2.2.0",
     "@rollup/plugin-commonjs": "20.0.0",
+    "@rollup/plugin-json": "4.1.0",
     "@rollup/plugin-node-resolve": "13.0.5",
+    "rollup": "^2.57.0",
+    "rollup-plugin-replace": "2.2.0",
     "rollup-plugin-sourcemaps": "0.6.3",
     "rollup-plugin-typescript2": "0.30.0",
     "rollup-plugin-uglify": "6.0.4",