Implemented a detection of hardware decoding used in pipeline

Simple check for names of decoder inside uridecodebin and cross check
with the list of known hardware Decoder Names

GstToolkit.h

@@ -22,6 +22,7 @@ std::string gst_version();
 
 std::list<std::string> all_plugins();
 std::list<std::string> enable_gpu_decoding_plugins(bool enable = true);
+std::string used_gpu_decoding_plugins(GstElement *gstbin);
 
 std::list<std::string> all_plugin_features(std::string pluginname);
 bool enable_feature (std::string name, bool enable);