Restructure include paths

include/backend/cuda/kernels/convolution.cuh

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <cuda_runtime.h>
+#include "layer.hpp"
+
+namespace CUDANet::Kernels {
+
+__global__ void convolution(
+    const float* __restrict__ d_input,
+    const float* __restrict__ d_kernel,
+    const float* __restrict__ d_bias,
+    float* __restrict__ d_output,
+    const Shape input_shape,
+    const Shape padding_shape,
+    const Shape kernel_shape,
+    const Shape stride_shape,
+    const Shape output_shape
+);
+
+}  // namespace CUDANet::Kernels