* Implement new system for individual user settings
* Fix some styling for NC core
* General styling fixes for apps
* Implement new enforce theme system to replace the enabled by default system
The old system doesn't really work with the new theming system in Nextcloud, so this new system is needed to achieve similar, although different, functionality.
* Don't allow user to enable / disable the theme if the theme is enforced (it would have no effect)
* Remove all references to icon variables as they no longer exist
* Implement repair step to migrate user settings
* Add option to enable / disable Breeze Dark depending on the client's system settings. This uses the prefers-color-scheme media query to determine whether to apply the theme or not.
Co-authored-by: bela <bela@firstnode.eu>
Co-authored-by: untbu <git@firstnode.eu>
