The vtkm::cont::ConvertNumComponentsToOffsets method was originally
created before vtkm::cont::DeviceAdapterId and the dynamic
vtkm::cont::Algorithm classes were created. Thus, it contained its own
version of TryExecute and did not support the direct selection of a
device at runtime. Change the function to use the new dynamic device
adapter id, which makes this more consistent with the rest of VTK-m and
cleans up the implementation quite a bit.