Provide a method to inject Webpack config

[Elius94]

The only reason for me to execute the "eject" command is that in my apps I am used to create frameless windows, so that I can create a custom titlebar etc. To do so, it is mandatory to set the "window" object of webpack with "frame: false":

  "window": {
    "frame": false,
    "toolbar": false,
    "show": false
  },

This is only possible if you eject the app. Please add the possibility to do this without ejecting

[naviapis]

@Elius94 I think frameless window works by adding it in package.json.

 {
   "name": "my-app",
   "version": "0.1.0",
   "private": true,
   "main": "index.html",
   // ...
+  "window": {
+    "frame": false,
+    "toolbar": false,
+    "show": false
+  }
 }