[BLAS, hipSYCL] Add CUDA_CUDA_LIBRARY to also link against libcuda.so

[nilsfriess]

Description

PR #228 added calls to cuStreamSynchronize in the cuBLAS backend. This function is located in libcuda.so but this library is not linked against when using hipSYCL to compile oneMKL. This PR adds CUDA_CUDA_LIBRARY in FindcuBLAS.cmake to fix this.

Checklist

• Do all unit tests pass locally? Attach a log.
  The tests do not pass currently on my setup, see [cuBLAS] cuBLAS test sometimes segfaults with dpc++ and hipSYCL #245, but it seems very unlikely that this is related to the change in this PR.
• Have you formatted the code using clang-format?
  Does not apply here.

[mkrainiuk]

Thank you for the fix! The changes look good to me.

[andrewtbarker]

Looks good, thanks!