Fix issues with VTK / VTK-m array conversion#

Changed the VTK to VTK-m array conversion routines to use ArrayHandleRuntimeVec and ArrayHandleRecombineVec. These are new features of VTK-m that allow you to specify an array with the tuple size specified at runtime. This change improves several specific things.

  • Fixes a bug when importing an array of “odd” tuple size (not 1, 2, 3, 4, 6, or 9). It was creating arrays of size one less than the actual size.

  • Avoids using ArrayHandleGroupVecVariable, which is supported by fewer VTK-m filters.

  • The VTK-m ArrayHandle now manages a reference back to the VTK array, so the ArrayHandle will continue to work even if the original VTK array is “deleted.” This makes the code safer.

  • Unifies the implementation of the array conversion among number of components to avoid issues with surprise tuple sizes.

  • Revamped vtkmDataArray to support general array types. This makes it more efficient to pass data from VTK-m to VTK when unified memory is not available.