refs https://github.com/TryGhost/DevOps/issues/80
- as part of moving Admin-X-Setting towards GA, we want to change it from
loading the settings externally via a CDN, to bundling it in with
Admin
- the bulk of the changes here are removing the config in Ghost, setting
up the copy to the Admin assets dir, and loading the new path in Admin
- several other changes have come along the way as I've cleaned up
unneeded code
refs https://github.com/TryGhost/Team/issues/3151
- adds route in Admin for opening new settings screen in react
- adds new config for passing `adminX` to Admin
- loads adminX settings from package in Admin UI when new route is opened
Co-authored-by: Peter Zimon <zimo@ghost.org>
