Add demosaicing wrapper

[l0rem1psum]

I have added the wrapper for both cuda and non-cuda version of the demosaicing function.

The unit test for non-cuda demosaicing is completed but I have yet to write a UT for the cuda version because there seems to be a compilation error there which I think I may not be best equipped to address that.

Would be happy to write UT for cuda demosaicing once those errors are fixed.