CUDA: add conv_2d_dw (#14265)

* CUDA: add conv_2d_dw

* better naming

* simplify using template

* Review: fix operation ordering in ggml-cuda, use __forceinline__, use more const

ggml/src/ggml-cuda/conv2d-dw.cuh

@@ -0,0 +1,5 @@
+#pragma once
+#include "common.cuh"
+
+#define CUDA_CONV2D_DW_BLOCK_SIZE 256
+void ggml_cuda_op_conv2d_dw(ggml_backend_cuda_context & ctx, ggml_tensor * dst);