[HIPIFY] Initial cuDNN support

- based on https://github.com/ROCmSoftwarePlatform/hipDNN.
- lit testing was supplemented with CUDA_DNN_ROOT_DIR for cuDNN testing.
- single cuDNN test was added.


[ROCm/hip commit: fe421c89b2]

projects/hip/hipify-clang/src/HipifyAction.cpp

@@ -160,6 +160,10 @@ bool HipifyAction::Exclude(const hipCounter & hipToken) {
                         insertedRANDHeader = true;
                         return false;
                     }
+                case API_DNN:
+                  if (insertedDNNHeader) { return true; }
+                    insertedDNNHeader = true;
+                    return false;
                 default:
                     return false;
             }