Codechange: Split CT_INVALID into CT_INVALID and INVALID_CARGO.

INVALID_CARGO is a CargoID and should be used for most purposes in game.
CT_INVALID is a CargoType used for defining default properties.

src/saveload/afterload.cpp

@@ -3029,13 +3029,13 @@ bool AfterLoadGame()
 		/* Make sure added industry cargo slots are cleared */
 		for (Industry *i : Industry::Iterate()) {
 			for (auto it = std::begin(i->produced) + 2; it != std::end(i->produced); ++it) {
-				it->cargo = CT_INVALID;
+				it->cargo = INVALID_CARGO;
 				it->waiting = 0;
 				it->rate = 0;
 				it->history = {};
 			}
 			for (auto it = std::begin(i->accepted) + 3; it != std::end(i->accepted); ++it) {
-				it->cargo = CT_INVALID;
+				it->cargo = INVALID_CARGO;
 				it->waiting = 0;
 			}
 			/* Make sure last_cargo_accepted_at is copied to elements for every valid input cargo.