[Feature request] Add checkbox to apply corresponding palette to theme automatically

[stefonarch]

We have some palette with the theme name, setting automatically those when switching theme would be a nice improvement as theming itself is still quite complicated, therefor adding a checkbox checked by default in lxqt-config-appearance.

If no corresponding name is present in /usr/share/lxqt/palettes/ switch to default light palette.

Expected Behavior

It applies palette allover

Current Behavior

User has to explicitly set it.