Restructure cuda backend

src/backends/cuda/utils/cuda_helper.cu

@@ -0,0 +1,26 @@
+#include <cuda_runtime.h>
+
+#include <cstdio>
+#include <cstdlib>
+
+#include "cuda_helper.cuh"
+
+cudaDeviceProp initializeCUDA() {
+    int deviceCount;
+    CUDA_CHECK(cudaGetDeviceCount(&deviceCount));
+
+    if (deviceCount == 0) {
+        std::fprintf(stderr, "No CUDA devices found. Exiting.\n");
+        std::exit(EXIT_FAILURE);
+    }
+
+    int device = 0;
+    CUDA_CHECK(cudaSetDevice(device));
+
+    cudaDeviceProp deviceProp;
+    CUDA_CHECK(cudaGetDeviceProperties(&deviceProp, device));
+
+    std::printf("Using CUDA device %d: %s\n", device, deviceProp.name);
+
+    return deviceProp;
+}