COMP: Avoid including VTK_USE_FILE within ITK

A convenient way to load VTK for usage in a project's CMakeLists.txt
file is

find_package(VTK)
include(${VTK_USE_FILE})

Doing this within ITK can cause mysterious linker and include path
problems for projects that use ITK and perform their own inclusion of
VTK_USE_FILE, a file that is meant to be included only once in a CMake
project.

This commit changes ITK's inclusion of VTK in the VtkGlue and
LevelSetsv4Visualization modules to not include VTK_USE_FILE.
Instead, it uses the vtk_module_config() mechanism to load the
necessary VTK modules and sets up only the necessary libraries,
include paths, and compiler definitions needed for each ITK module.

This change should make it possible for projects that use ITK with
VtkGlue and/or LevelSetsv4Visualization enabled with the simplified
idiom

find_package(VTK)
include(${VTK_USE_FILE})

as long as ITK is found prior to VTK, i.e.,

find_package(ITK)
find_package(VTK)

Change-Id: Ic54e09890617bf8b81f0aba672b573a5bdf5e7bf
Merge topic 'improve_vtk_inclusion'

6274e5fd COMP: Avoid including VTK_USE_FILE within ITK