Core/BattlegroundIC:

* Fixed Catapults
* Fixed Graveyards
* Fixed Cannons on Gunships
* More Blizzlike Teleport to Gunship
* Fixed Gunship Teleport to Hangar

Closes https://github.com/TrinityCore/TrinityCore/issues/12323 and https://github.com/TrinityCore/TrinityCore/issues/9557

But it's not yet finished...

Missing waypoints (captains on transport)
Some hacks... (like in spell_ioc_gunship_portal)

Should I use CreateNPCPassenger or SummonPassenger for adding creatures to transports ?
does SummonPassenger() always return a valid not-NULL pointer ?