Instead of tracking variables in cmakex_cache_tracker we should simplify the whole cmakex:
remove cmakex_cache_tracker, use CMakeCache.txt, maybe keep track which variables has been changed but maybe that's not even necessary
use install/file/dir times to find out if something needs to be reconfigured/rebuilt
the whole point of cmakex_cache_tracker was to allow installing prebuilt binaries and know their exact build options. But prebuilding binaries should anyway must be done in a full clean-build environment in one single clean step (launch the building process and wait for the end artifact) so there's no need to keep track of variables there
Instead of tracking variables in cmakex_cache_tracker we should simplify the whole cmakex: