Adding tensor contraction operation backend for Sycl; adding test for contractionOp sycl backend; adding temporary solution to prevent memory leak in buffer; cleaning up cxx11_tensor_buildins_sycl.h

unsupported/Eigen/CXX11/src/Tensor/TensorSyclRun.h

@@ -56,7 +56,6 @@ void run(Expr &expr, Dev &dev) {
     });
       dev.synchronize();
   }
-
   evaluator.cleanup();
 }
 }  // namespace TensorSycl