[GTK Config] Parameterise GTK config editing
This diff is only touches the editing part of the ConfigEditor.
- Pass config values as the respecting types: int, bool and string. This simplifies config editing in some extent - no more hardcoded options names, that requires quotes around values in gtkrc-2.0 and xsettingsd.conf. Also it simplifies working with GSettings API and helps to transform KDE config options to GTK config options.
- Remove redundant \\n symbols, when adding new option in gtkrc-2.0 and xsettingsd.conf
- Restart Kded
- Test all settings syncing. Specifically boolean ones and enum ones, as the format in configuration files has changed:
- Settings.ini uses new booleans (true and false instead of 1 and 0)
- Settings.ini, .gtkrc-2.0 and xsettingsd.conf use int value of enum instead of string
Reviewers: Plasma, cblack
Reviewed By: Plasma, cblack
Differential Revision: https://phabricator.kde.org/D27100