BUG: Don't store style settings per version

Move the settings location where the user's selected style and
additional style paths are stored from the per-version store to the
general user store, as there is no particular reason why these would be
version specific, and having to set them after every update (especially
in a developer environment) is a little annoying.

Issue #3691

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23174 3bd1e089-480b-0410-8dfb-8563597acbee