Kept the infrastructure to allow re-introducing it later if a better source for a device key is found.
Added support for not having any valid settings encryption key.
Added warnings if the user is running without a settings encryption key.
Added additional checks during startup to help with troubleshooting and configuring a setup with a settings encryption key.
Docker builds will now warn if no encryption key is set.
This fixes#5518
Re-implemented everything using ASP.NET.
Changed some requests to use JSON instead of FORM data.
Some work towards deleting the FIXMEGlobal instance.
Auth is missing, XSRF does not work correctly.