vtkm: update for install layout fixes in embedded diy
Also brings in:
- Deprecation of FilterCell
- runtime-selectable buffer count for ArrayHandle
- kokkos backend
- support for ArrayHandle::DeepCopy
- MPI streamlines
- split up vtkm_filter library
- free atomic functions
- use of Buffer in ArrayHandleSOA and ArrayHandleBitField
- Storage is now stateless
- vtkm::Massless is now vtkm::Particle
Maybe this update is a bit ambitious...