GPU Cholesky optimization, solves #109
- Added elpa_gpu_ccl_transpose_vectors in Cholesky-GPU
- Extract memcpy of info outside of cublas?potrf
- Move nccl_group_start out of the loops
- delete unused vendor_agnostic_layer_template.F90
- Add new cusolverDnXpotrf interface (cusolverDn?potrf is deprecated)