We have lots of inconsistency at the moment in CMakeLists.txt files. Most
of it is due to kwin being a very old project. This change hopefully fixes
all of it.
All KCMs and KWin core use the BuiltInEffects namespace to find and
interact with the effects. There is no information left in the desktop
file which are of usage. Thus they can be removed.
* this effect is way cheaper than blur, don't cache it
* use its own atom
* also pass the matrix in the x property
* remove remnants of the cache
* do just a single pass
* get rid of config ui remnants
* a copy of the blur shader to become a copy of the background contrast effect
* contrastshader actually doing the light modification
* don't expand/shrink the area
