Separate UI from applying configuration by implementing proper
anaconda/kickstart addon. This have multiple benefits:
- entering settings window twice does not result in configuration being
applied multiple times
- all settings can be saved and loaded in kickstart file - this allows
automating this part of installation too
- it's much easier to implement other UI (text) for the same mechanism
There is one little catch: initial-setup (contrary to base anaconda)
does not provide graphical indicator for long-running system
configuration, so while configuration is progress, the UI is frozen.
Workaround this by re-using old progress dialog, but from kickstart
addon this time. This means the kickstart needs to know whether it's
running from GUI or not.
FixesQubesOS/qubes-issues#2433
(backported from R4.1, adjusted for older anaconda)
556b584f74