Rooted vehicle movement (#13342 for example)

Corrects issue where certain combinations of actions would cause vehicles (usually cannons/artillary) that should be rooted, to be fully movable

src/server/game/Entities/Unit/Unit.cpp

@@ -16975,6 +16975,12 @@ void Unit::_EnterVehicle(Vehicle* vehicle, int8 seatId, AuraApplication const* a
         }
     }
 
+    // If vehicle flag for fixed position set (cannons), or if the following hardcoded units, then set state rooted
+    //  30236 | Argent Cannon
+    //  39759 | Tankbuster Cannon
+    if ((vehicle->GetVehicleInfo()->m_flags & VEHICLE_FLAG_FIXED_POSITION) || vehicle->GetBase()->GetEntry() == 30236 || vehicle->GetBase()->GetEntry() == 39759)
+        SetControlled(true, UNIT_STATE_ROOT);
+
     ASSERT(!m_vehicle);
     (void)vehicle->AddPassenger(this, seatId);
 }