Rename "site_name" to actual "name" manifest.json entry and adjust required form fields.

Done, please review!

I know, that at least for chromium based browsers, only "name", "icons", "start_url" and "display" is required. But all the other required fields, here, are set indirectly. For example, if "scope" is not set, the scope will be based on the "start_url". Or if "theme_color" is not set, it will fall back to #ffffff. So making these fields required and setting the fallback value inside the pwa.config.yml only makes sense here. So the user knows, what setting he is actual using.

Please do a manual test (running the update hook and testing the settings) once finished, then it should be fine! :)

Tested the update hook, works great! Please rereview!

Perfect! Merged!!

Automatically closed - issue fixed for 2 weeks with no activity.