Codechange: Make order load/unload flags value types. (#14861)

Order Load and Unload flags have complex logic to ensure that invalid combinations aren't used. In fact, apart from FullLoad and FullLoadAny, all mixed combinations are invalid.

Simplify logic by removing the use of bit values and treat each option as a value.

src/cargopacket.cpp

@@ -425,14 +425,14 @@ void VehicleCargoList::AgeCargo()
  * @param accepted If the cargo will be accepted at the station.
  * @param current_station ID of the station.
  * @param next_station ID of the station the vehicle will go to next.
- * @param order_flags OrderUnloadFlags that will apply to the unload operation.
+ * @param unload_type OrderUnloadType that will apply to the unload operation.
  * @param ge GoodsEntry for getting the flows.
  * @param cargo The cargo type of the cargo.
  * @param payment Payment object for registering transfers.
  * @param current_tile Current tile the cargo handling is happening on.
  * return If any cargo will be unloaded.
  */
-bool VehicleCargoList::Stage(bool accepted, StationID current_station, std::span<const StationID> next_station, uint8_t order_flags, const GoodsEntry *ge, CargoType cargo, CargoPayment *payment, TileIndex current_tile)
+bool VehicleCargoList::Stage(bool accepted, StationID current_station, std::span<const StationID> next_station, OrderUnloadType unload_type, const GoodsEntry *ge, CargoType cargo, CargoPayment *payment, TileIndex current_tile)
 {
 	this->AssertCountConsistency();
 	assert(this->action_counts[MTA_LOAD] == 0);
@@ -444,9 +444,9 @@ bool VehicleCargoList::Stage(bool accepted, StationID current_station, std::span
 	static const FlowStatMap EMPTY_FLOW_STAT_MAP = {};
 	const FlowStatMap &flows = ge->HasData() ? ge->GetData().flows : EMPTY_FLOW_STAT_MAP;
 
-	bool force_keep = (order_flags & OUFB_NO_UNLOAD) != 0;
-	bool force_unload = (order_flags & OUFB_UNLOAD) != 0;
-	bool force_transfer = (order_flags & (OUFB_TRANSFER | OUFB_UNLOAD)) != 0;
+	bool force_keep = unload_type == OrderUnloadType::NoUnload;
+	bool force_unload = unload_type == OrderUnloadType::Unload;
+	bool force_transfer = unload_type == OrderUnloadType::Transfer || unload_type == OrderUnloadType::Unload;
 	assert(this->count > 0 || it == this->packets.end());
 	while (sum < this->count) {
 		CargoPacket *cp = *it;