Merge cache creation from settings and from TCK
This merges !27 (closed) and what is currently installed in the pit https://gitlab.cern.ch/lhcb/Moore/blob/raaij-HltCache/
- by default, the cache is build from settings (in split mode)
- cache is built for TCKs if a list is specified in tcks.cmake. In this case, the cache from settings is skipped
- this supersedes !27 (closed)