It has been a while since anyone has really touched the interop library. These changes add a vtkm-interop library that encapsulates all of the code to transfer arrays from VTK-m to OpenGL. The one function, TransferToOpenGL now takes a VariantArrayHandle that passes the array through a library boundary.
The interop library also no longer relies on the VTK-m render library. Chances are if someone is using OpenGL interop they are using their own rendering code.