IVGCVSW-3541 Get the paths where to load the dynamic backends from

 * Adds GetBackendPaths and IsPathValid to DynamicBackendUtils
 * Adds related unit tests

Change-Id: I94e377d92a88a4b5d48026f6ad5b4d5387d20c21
Signed-off-by: Jan Eilers <jan.eilers@arm.com>
Signed-off-by: Matteo Martincigh <matteo.martincigh@arm.com>
diff --git a/cmake/GlobalConfig.cmake b/cmake/GlobalConfig.cmake
index 26b3ff4..8dad57a 100644
--- a/cmake/GlobalConfig.cmake
+++ b/cmake/GlobalConfig.cmake
@@ -19,6 +19,7 @@
 option(FLATC_DIR "Path to Flatbuffers compiler" OFF)
 option(TF_LITE_GENERATED_PATH "Tensorflow lite generated C++ schema location" OFF)
 option(FLATBUFFERS_ROOT "Location where the flatbuffers 'include' and 'lib' folders to be found" Off)
+option(DYNAMIC_BACKEND_PATHS "Colon seperated list of paths where to load the dynamic backends from" "")
 
 include(SelectLibraryConfigurations)