VECGEOM-280: Refactoring of navigation classes to use VecCore + bug fix in navigation
a) Important step to move to VecCore:
- make navigation classes independent of Vc
- use VecCore types and constructs
- combine scalar and vector kernels
- now also ready for UMESIMD, etc...
b) This merge request should also solve navigation problems in Geant-V which appeared after the recent move to new Box. This was due due to a missing implementation of a vector API which was fixed here.