IVGCVSW-4874 Provide LayerSupportHandle to frontend users

 * Add test for new IsBackendRegistered member function of Handle
 * Move deprecated messages to new frontend API of LayerSupportHandle
 * Update delegate to use dot operator for IsXXXLayerSupported

Signed-off-by: Francis Murtagh <francis.murtagh@arm.com>
Change-Id: I70d7166e207a10e4b3583a827ca0dda2169bcba1
!android-nn-driver:4940
diff --git a/delegate/src/DelegateUtils.hpp b/delegate/src/DelegateUtils.hpp
index 58eeb9a..17261e4 100644
--- a/delegate/src/DelegateUtils.hpp
+++ b/delegate/src/DelegateUtils.hpp
@@ -29,11 +29,11 @@
     for (auto&& backendId : backends) \
     { \
         auto layerSupportObject = armnn::GetILayerSupportByBackendId(backendId); \
-        if (layerSupportObject) \
+        if (layerSupportObject.IsBackendRegistered()) \
         { \
             std::string reasonIfUnsupported; \
             supported = \
-                layerSupportObject->func(__VA_ARGS__, armnn::Optional<std::string&>(reasonIfUnsupported)); \
+                layerSupportObject.func(__VA_ARGS__, armnn::Optional<std::string&>(reasonIfUnsupported)); \
             if (supported) \
             { \
                 break; \