elementwise op (#238)

* Add elementwise operation kernel and example

* Add comment

* Add template argument of dim . Prepare to support multiple dimension

* Rename example

* Support 1 dimension

* Add static assert

* Add comment

* Extract pad

* Remove redundant argument

* Support any dimension for elementwise operation

* Remove line

* Let it be the multiple number of CU

* Move thread per block to the parameter of constructor

* rename threadPerBlock with blockSize

* Support double

* rename kernel function name

* remove redundant include header

* Refine type

* Need to the final dimension

* Refine variable name

* Refine type

* Use index_t instead of int in API

Co-authored-by: rocking <chunylai@amd.com>

include/ck/tensor_operation/gpu/element/binary_element_wise_operation.hpp

@@ -0,0 +1,25 @@
+#pragma once
+#include "data_type.hpp"
+
+namespace ck {
+namespace tensor_operation {
+namespace binary_element_wise {
+
+struct Add
+{
+    __host__ __device__ constexpr void
+    operator()(double& dst, const double& src1, const double& src2) const
+    {
+        dst = src1 + src2;
+    }
+
+    __host__ __device__ constexpr void
+    operator()(float& dst, const float& src1, const float& src2) const
+    {
+        dst = src1 + src2;
+    }
+};
+
+} // namespace binary_element_wise
+} // namespace tensor_operation
+} // namespace ck