IVGCVSW-2915 Add Merge Layer and no-op factory method

Change-Id: I54549671e0d3b207904cf9796a843eb2b0a631f7
Signed-off-by: Nattapat Chaimanowong <nattapat.chaimanowong@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index ec237aa..d1fe635 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -239,6 +239,8 @@
     src/armnn/layers/MeanLayer.cpp
     src/armnn/layers/MemCopyLayer.hpp
     src/armnn/layers/MemCopyLayer.cpp
+    src/armnn/layers/MergeLayer.hpp
+    src/armnn/layers/MergeLayer.cpp
     src/armnn/layers/MergerLayer.hpp
     src/armnn/layers/MergerLayer.cpp
     src/armnn/layers/MinimumLayer.cpp