ENH: Allow ITKVideoBridgeOpenCV to be built externally.
ENH: Allow ITKVideoBridgeOpenCV to be built externally.

To closely follow the load pattern in ITK/CMake/ITKModuleEnablement.cmake,
itk-module-init.cmake is include'd after the inserted cmake_minimum_required
and before the project commands.

Change-Id: I273fd92e3f40f465cb26bcbb32599d068784ae29

BRAINSia/ITK,BRAINSia/ITK,malaterre/ITK,jcfr/ITK,richardbeare/ITK,Kitware/ITK,malaterre/ITK,stnava/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,jcfr/ITK,thewtex/ITK,stnava/ITK,richardbeare/ITK,PlutoniumHeart/ITK,fbudin69500/ITK,InsightSoftwareConsortium/ITK,blowekamp/ITK,zachary-williamson/ITK,blowekamp/ITK,hjmjohnson/ITK,vfonov/ITK,richardbeare/ITK,fbudin69500/ITK,stnava/ITK,zachary-williamson/ITK,vfonov/ITK,malaterre/ITK,spinicist/ITK,spinicist/ITK,fbudin69500/ITK,hjmjohnson/ITK,BRAINSia/ITK,thewtex/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,Kitware/ITK,LucasGandel/ITK,BRAINSia/ITK,hjmjohnson/ITK,blowekamp/ITK,zachary-williamson/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,fbudin69500/ITK,malaterre/ITK,LucasGandel/ITK,jcfr/ITK,spinicist/ITK,LucasGandel/ITK,jcfr/ITK,fbudin69500/ITK,richardbeare/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,PlutoniumHeart/ITK,spinicist/ITK,hjmjohnson/ITK,BRAINSia/ITK,jcfr/ITK,InsightSoftwareConsortium/ITK,zachary-williamson/ITK,PlutoniumHeart/ITK,thewtex/ITK,malaterre/ITK,blowekamp/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,jcfr/ITK,blowekamp/ITK,stnava/ITK,zachary-williamson/ITK,vfonov/ITK,zachary-williamson/ITK,thewtex/ITK,stnava/ITK,malaterre/ITK,hjmjohnson/ITK,Kitware/ITK,stnava/ITK,fbudin69500/ITK,fbudin69500/ITK,spinicist/ITK,PlutoniumHeart/ITK,thewtex/ITK,BRAINSia/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,spinicist/ITK,jcfr/ITK,LucasGandel/ITK,vfonov/ITK,zachary-williamson/ITK,richardbeare/ITK,stnava/ITK,spinicist/ITK,jcfr/ITK,hjmjohnson/ITK,LucasGandel/ITK,spinicist/ITK,Kitware/ITK,spinicist/ITK,Kitware/ITK,blowekamp/ITK,LucasGandel/ITK,fbudin69500/ITK,zachary-williamson/ITK,PlutoniumHeart/ITK,vfonov/ITK,vfonov/ITK,richardbeare/ITK,LucasGandel/ITK,hjmjohnson/ITK,richardbeare/ITK,blowekamp/ITK,blowekamp/ITK,thewtex/ITK,PlutoniumHeart/ITK,zachary-williamson/ITK,thewtex/ITK,stnava/ITK,LucasGandel/ITK,BRAINSia/ITK,vfonov/ITK,Kitware/ITK,stnava/ITK