Revert "Remove dead code."

Not used by python, but is used by jinja templates.

This reverts commit 1f3eee90f148c7a7fdc442e1b403b3c9c2bcfac9.

game/factions/faction.py

@@ -25,6 +25,7 @@ from game.data.doctrine import (
     MODERN_DOCTRINE,
     WWII_DOCTRINE,
 )
+from game.data.groups import GroupRole
 from game.data.units import UnitClass
 from game.dcs.aircrafttype import AircraftType
 from game.dcs.groundunittype import GroundUnitType
@@ -154,6 +155,20 @@ class Faction:
         )
         return list(set(all_units))
 
+    @property
+    def air_defenses(self) -> list[str]:
+        """Returns the Air Defense types"""
+        # This is used for the faction overview in NewGameWizard
+        air_defenses = [a.display_name for a in self.air_defense_units]
+        air_defenses.extend(
+            [
+                pg.name
+                for pg in self.preset_groups
+                if any(task.role == GroupRole.AIR_DEFENSE for task in pg.tasks)
+            ]
+        )
+        return sorted(air_defenses)
+
     @classmethod
     def from_dict(cls: Type[Faction], json: Dict[str, Any]) -> Faction:
         faction = Faction(