[1/3] Add optional value type for vtkDataArray specialization of ValueRange and GetAPIType

• This merge request is fundamental to support external memory spaces in catalyst2. By external memory space, I mean a vtkDataArray subclass which wraps around an unmanaged memory allocation in an accelerator device like CUDA. As an example, vtkmDataArray may actually reference data that is only accessible on device.
• This work is pre-requisite for vtkCellArray to handle any type of connectivity and offset arrays, both of which could be in external memory spaces. It allows developers to enforce the value type of the ValueRange for generic data arrays which are not accessible in the form of a (derived) vtkAoSDataArrayTemplate instance. Ex: vtkmDataArray