Array dispatching significantly increases compile time. Using `clang`,
the prior `vtkDataArray.cxx` took almost 5 minutes to compile. By
splitting out the implementations into separate files, overall
compilation time is now 77 seconds on the same hardware (with 14
workers).

Sample timings (sample size of 1):

Time to complete CommonCore:

Before:  08:06.120
After:   05:03.382

Individual objects:

Before:

   04:51.551   vtkDataArray.cxx.o

After:

   00:01.746   vtkDataArray.cxx.o
   00:02.764   vtkDataArray_ScalarRange.cxx.o
   00:02.931   vtkDataArray_VectorRange.cxx.o
   00:02.955   vtkDataArray_FiniteScalarRange.cxx.o
   00:03.026   vtkDataArray_FiniteVectorRange.cxx.o
   00:08.553   vtkDataArray_InterpolateTuple_weights.cxx.o
   00:10.235   vtkDataArray_InsertTuples_array_idlist_range.cxx.o
   00:10.800   vtkDataArray_InterpolateTuple_time.cxx.o
   00:34.192   vtkDataArray_CopyComponent.cxx.o
   00:39.109   vtkDataArray_DeepCopy.cxx.o
   01:04:...