Add AEW&C aircraft to the faction aircraft list.

To avoid confusion, use only the aircraft list for the purchasable
aircraft. This fix also caught a faction's Tu-142 that was not actually
purchasable. Invalid aircraft in the faction aircraft list will now
raise an error.

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/1074

game/db.py

@@ -117,6 +117,7 @@ from dcs.planes import (
     Yak_40,
     plane_map,
     I_16,
+    Tu_142,
 )
 from dcs.ships import (
     Boat_Armed_Hi_speed,
@@ -456,6 +457,7 @@ PRICES = {
     Tu_160: 50,
     Tu_22M3: 40,
     Tu_95MS: 35,
+    Tu_142: 35,
     # special
     IL_76MD: 30,
     An_26B: 25,

game/factions/faction.py

@@ -154,6 +154,8 @@ class Faction:
         faction.awacs = load_all_aircraft(json.get("awacs", []))
         faction.tankers = load_all_aircraft(json.get("tankers", []))
 
+        faction.aircrafts = list(set(faction.aircrafts + faction.awacs))
+
         faction.frontline_units = load_all_vehicles(json.get("frontline_units", []))
         faction.artillery_units = load_all_vehicles(json.get("artillery_units", []))
         faction.infantry_units = load_all_vehicles(json.get("infantry_units", []))