IVGCVSW-7880 Add check for FP16 backend support

 * Check if preferred backends have FP16 support before enable fp16-turbo-mode
 * Unit tests
 * Replaced global gpuAccCapabilities with getter method construction
 * Replaced deprecated function call in SL shim

Signed-off-by: Narumol Prangnawarat <narumol.prangnawarat@arm.com>
Signed-off-by: Ryan OShea <ryan.oshea3@arm.com>
Change-Id: If29b62b330ca8987de8acf6408db11daf25ca0b5
diff --git a/src/backends/reference/RefBackend.hpp b/src/backends/reference/RefBackend.hpp
index ecbe4d5..7d355ea 100644
--- a/src/backends/reference/RefBackend.hpp
+++ b/src/backends/reference/RefBackend.hpp
@@ -1,5 +1,5 @@
 //
-// Copyright © 2022 Arm Ltd and Contributors. All rights reserved.
+// Copyright © 2022-2023 Arm Ltd and Contributors. All rights reserved.
 // SPDX-License-Identifier: MIT
 //
 #pragma once
@@ -18,7 +18,8 @@
                                                     {"PreImportIOTensors", true},
                                                     {"ExternallyManagedMemory", true},
                                                     {"MultiAxisPacking", false},
-                                                    {"SingleAxisPacking", true}
+                                                    {"SingleAxisPacking", true},
+                                                    {"HasFp16", true}
                                              });
 
 const std::set<armnn::BackendCapability> oldCpuRefCapabilities {