IVGCVSW-1913: Fix for ValidationTest.concat_float_3_relaxed

* Added RefPermuteFloat16Workload to serve as a fallback when CL
  does not support the required permute configuration for FP16
* Move Half.hpp to armnnUtils as the utils library should not be
  including private header files from the armnn library

Change-Id: Ibf0f698451e8406f7ed7cce470dab60b6d16361d
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8d77d91..39d83c2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,6 +27,7 @@
 set(armnnUtils_sources)
 list(APPEND armnnUtils_sources
     src/armnnUtils/GraphTopologicalSort.hpp
+    src/armnnUtils/Half.hpp
     src/armnnUtils/Logging.hpp
     src/armnnUtils/Permute.hpp
     src/armnnUtils/Logging.cpp
@@ -219,7 +220,6 @@
     src/armnn/layers/SplitterLayer.cpp
     src/armnn/layers/SubtractionLayer.cpp
     src/armnn/layers/SubtractionLayer.hpp
-    src/armnn/Half.hpp
     src/armnn/InternalTypes.hpp
     src/armnn/InternalTypes.cpp
     src/armnn/JsonPrinter.hpp