Add: [Script] GetAirportNumHelipads (#12085)

Adds a function for Scripts to get the number of helipads of an airport type.

src/script/api/ai_changelog.hpp

@@ -22,6 +22,7 @@
  * \li AITown::ROAD_LAYOUT_RANDOM
  * \li AIVehicle::IsPrimaryVehicle
  * \li AITileList_StationCoverage
+ * \li AIAirport::GetAirportNumHelipads
  *
  * API removals:
  * \li AIError::ERR_PRECONDITION_TOO_MANY_PARAMETERS, that error is never returned anymore.

src/script/api/game_changelog.hpp

@@ -88,6 +88,7 @@
  * \li GSStoryPage::IsValidStoryPageButtonFlags
  * \li GSStoryPage::IsValidStoryPageButtonCursor
  * \li GSTileList_StationCoverage
+ * \li GSAirport::GetAirportNumHelipads
  *
  * API removals:
  * \li GSError::ERR_PRECONDITION_TOO_MANY_PARAMETERS, that error is never returned anymore.

src/script/api/script_airport.cpp

@@ -170,3 +170,10 @@
 
 	return (int64_t)GetMaintenanceCostFactor(type) * _price[PR_INFRASTRUCTURE_AIRPORT] >> 3;
 }
+
+/* static */ SQInteger ScriptAirport::GetAirportNumHelipads(AirportType type)
+{
+	if (!IsAirportInformationAvailable(type)) return -1;
+
+	return ::AirportSpec::Get(type)->fsm->num_helipads;
+}

src/script/api/script_airport.hpp

@@ -207,6 +207,14 @@ public:
 	 * @return Monthly maintenance cost of the airport type.
 	 */
 	static Money GetMonthlyMaintenanceCost(AirportType type);
+
+	/**
+	 * Get the number of helipads of this airport type.
+	 * @param type The airport type.
+	 * @pre IsAirportInformationAvailable(type)
+	 * @return Number of helipads of this type of airport. When 0 helicopters will go to normal terminals.
+	 */
+	static SQInteger GetAirportNumHelipads(AirportType type);
 };
 
 #endif /* SCRIPT_AIRPORT_HPP */