When Python support is enabled, on Unix machines, a new option named
PARAVIEW_FREEZE_PYTHON is available. When ON, ParaView will freeze python
modules into the executable. This currently doesn't support matplotlib or numpy.

vtkUtilitiesPythonInitializer module runs vtkFreezePython.cmake to freeze the
python modules and includes the initialization logic in vtkPVPythonInitializer
initialization calls itself.

Change-Id: I5e299374746a872eb9ff3f89beeb5ed2227d6f58