VideoBackend: Rename GetName to GetConfigName

Make the function name more explicit and a better match for
GetDisplayName.

Change NAME to CONFIG_NAME while I'm at it.

Source/Core/Core/DolphinAnalytics.cpp

@@ -370,7 +370,7 @@ void DolphinAnalytics::MakePerGameBuilder()
   builder.AddData("cfg-render-to-main", Config::Get(Config::MAIN_RENDER_TO_MAIN));
   if (g_video_backend)
   {
-    builder.AddData("cfg-video-backend", g_video_backend->GetName());
+    builder.AddData("cfg-video-backend", g_video_backend->GetConfigName());
   }
 
   // Video configuration.