Single-kernel GEMM + layernorm (#263)

* dump lds content in appropriate precision type

* add squared add reduction op; allows sq sum

* initial stub from regular gemm impl

* layernorm example code & host verification

* initial layernorm implementation

* tidy up

* make C0 precision type consistent with C

* clang-tidy and additional comments

* tighten up example code

* account for extra flops/bytes from normalization

* clang-format

* c0 bias/beta/gamma now have its own precision type

* AccElemOp for gemm outputs prior to feeding to layernorm

* update workgroup mapping

* rename kernel template param to reflect its dual use

* use LDS mem pool for reduction workspace

* change cshuffle precision type to f16; clean up

* clang-format

* correct naming

* explicit cast

* fully implemented gemm + bias + activation + add + norm

* activation in correct order

* reflect reduction API's recent change

* amend

* clean up; add comment

* keep up with recent changes in reduction API

* format

* resolve merge conflicts

Co-authored-by: Chao Liu <chao.liu2@amd.com>

include/ck/tensor_operation/gpu/thread/reduction_functions_threadwise.hpp

@@ -30,6 +30,8 @@ struct ThreadwiseReduction
 
     static_assert(src_length_m == dst_length_m, "lengths of source and dst buffer must match!");
 
+    using Op = OpReduce;
+
     template <typename SrcBufferType, typename DstBufferType>
     __device__ static void Reduce(const SrcBufferType& src_buf, DstBufferType& dst_buf)
     {