build(ITKVtkGlue): Use the external repository
build(ITKVtkGlue): Use the external repository

Also specify VTK_RENDERING_BACKEND is None because there are missing
symbols.

thewtex/ITKBridgeJavaScript,thewtex/ITKBridgeJavaScript,thewtex/ITKBridgeJavaScript,InsightSoftwareConsortium/ITKBridgeJavaScript,InsightSoftwareConsortium/ITKBridgeJavaScript,InsightSoftwareConsortium/ITKBridgeJavaScript