Add: [Script] ScriptCargo::GetName, to get the human readable name of a cargo (#8544)

Of course this translates into AICargo.GetName() for AIs and
GSCargo.GetName() for GameScripts.

src/script/api/game_changelog.hpp

@@ -18,6 +18,7 @@
  * This version is not yet released. The following changes are not set in stone yet.
  *
  * API additions:
+ * \li GSCargo::GetName
  * \li GSEventStoryPageButtonClick
  * \li GSEventStoryPageTileSelect
  * \li GSEventStoryPageVehicleSelect