COMP: Update examples to the new build system to avoid warnings

[dzenanz]

Warning that was triggered:

CMake Warning (dev) at CMake/UseITK.cmake:28 (message):
  CMake/UseITK.cmake is deprecated.

  Please update CMakeLists.txt to use `find_package(ITK)` and link to
  "${ITK_INTERFACE_LIBRARIES}".

Call Stack (most recent call first):
  Modules/Remote/Montage/examples/CMakeLists.txt:23 (include)
This warning is for project developers.  Use -Wno-dev to suppress it.

[dzenanz]

@blowekamp Trying to build locally in C:/Dev/ITK-vs26 by setting Module_Montage_GIT_TAG=a94b01789bf21add8eed68773ae44ea3f864c7b7 and BUILD_EXAMPLES=ON, I run into:

CMake Error at CMake/ITKModuleAPI.cmake:87 (message):
  No such module: "Montage"
Call Stack (most recent call first):
  CMake/ITKModuleAPI.cmake:31 (itk_module_load)
  CMake/ITKModuleAPI.cmake:148 (_itk_module_config_recurse)
  C:/Dev/ITK-vs26-rider/ITKConfig.cmake:94 (itk_module_config)
  Modules/Remote/Montage/examples/CMakeLists.txt:16 (find_package)

Manually setting ITK_DIR to C:/Dev/ITK-vs26 gets overwritten by C:/Dev/ITK-vs26-rider upon clicking "Configure".

[blowekamp]

LGTM