[SYCL][CUDA] Remove opencl-headers dependency from pi-cuda.h

[Ruyk]

From #1260:

There are also various places in the SYCL RT that simply assume CL types, such as the interop functions, so the opencl-headers are required to build the project anyway.

Things like this are plug-in specific and should reside in plug-in specific headers:
pi-opencl.h <-- interop with OpenCL
pi-cuda.h <-- interop with CUDA

Without pulling the opencl-headers, the build system in some cases picks up the OpenCL 1.2 headers from NVIDIA and creates more build problems.

We should use only CUDA plug-in on platform and this plug-in should not include OpenCL headers. This will resolve the problem.

Is it a major problem if the dependency is there @bader ?

No for this patch. I already approved it.

Originally posted by @bader in #1260 (comment)