Improve custom panel support

[balloob]

Add support for:

• JS based custom panels
• Embedding custom panels in iframes (optional) (allows React based panels)
• Confirming with user if they want to load an external panel
• Allow trusting individual external panels to be loaded without confirmation

Backend PR home-assistant/core#14708
Starter kit example for React based panel: https://github.com/home-assistant/custom-panel-starter-kit-react

Config example:

# Configuration.yaml example
panel_custom:
  - name: react-panel
    url_path: react-panel-prod
    sidebar_title: React Prod
    sidebar_icon: mdi:react
    js_url: https://s3.amazonaws.com/home-assistant-demos/panel-examples/react-demo.js
    embed_iframe: true
    config:
      name: World

[c727]

Afaik confirm does not work on mobile Safari or the iOS App

[balloob]

https://stackoverflow.com/questions/18903525/alert-and-confirm-not-working-with-apple-mobile-web-app-capable

Fixed in iOS 7.0.3 according to this StackOverflow.

[c727]

panel.config.config is a bit odd, we will get a 2nd release with many forum posts about XXX is broken

[balloob]

Ok, fair point. I have an idea how to fix it. It means that we're going to keep panel config as panel.config and then have panel.config._custom_panel be our config.

[balloob]

👍 done!