Change squadrons to operate out of a single base.

https://github.com/dcs-liberation/dcs_liberation/issues/1145

Currently this is fixed at the start of the campaign. The squadron
locations are defined by the campaign file.

Follow up work:

* Track aircraft ownership per-squadron rather than per-airbase.
* UI for relocating squadrons.
* Ferry missions for squadrons that are relocating.
* Auto-relocation (probably only for retreat handling).

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/1138

game/campaignloader/squadrondefgenerator.py

@@ -0,0 +1,82 @@
+from __future__ import annotations
+
+import itertools
+import random
+from typing import TYPE_CHECKING, Optional
+
+from game.dcs.aircrafttype import AircraftType
+from game.squadrons.operatingbases import OperatingBases
+from game.squadrons.squadrondef import SquadronDef
+from game.theater import ControlPoint
+from gen.flights.ai_flight_planner_db import aircraft_for_task, tasks_for_aircraft
+from gen.flights.flight import FlightType
+
+if TYPE_CHECKING:
+    from game.coalition import Coalition
+
+
+class SquadronDefGenerator:
+    def __init__(self, coalition: Coalition) -> None:
+        self.coalition = coalition
+        self.count = itertools.count(1)
+        self.used_nicknames: set[str] = set()
+
+    def generate_for_task(
+        self, task: FlightType, control_point: ControlPoint
+    ) -> Optional[SquadronDef]:
+        aircraft_choice: Optional[AircraftType] = None
+        for aircraft in aircraft_for_task(task):
+            if aircraft not in self.coalition.faction.aircrafts:
+                continue
+            if not control_point.can_operate(aircraft):
+                continue
+            aircraft_choice = aircraft
+            # 50/50 chance to keep looking for an aircraft that isn't as far up the
+            # priority list to maintain some unit variety.
+            if random.choice([True, False]):
+                break
+
+        if aircraft_choice is None:
+            return None
+        return self.generate_for_aircraft(aircraft_choice)
+
+    def generate_for_aircraft(self, aircraft: AircraftType) -> SquadronDef:
+        return SquadronDef(
+            name=f"Squadron {next(self.count):03}",
+            nickname=self.random_nickname(),
+            country=self.coalition.country_name,
+            role="Flying Squadron",
+            aircraft=aircraft,
+            livery=None,
+            mission_types=tuple(tasks_for_aircraft(aircraft)),
+            operating_bases=OperatingBases.default_for_aircraft(aircraft),
+            pilot_pool=[],
+        )
+
+    @staticmethod
+    def _make_random_nickname() -> str:
+        from gen.naming import ANIMALS
+
+        animal = random.choice(ANIMALS)
+        adjective = random.choice(
+            (
+                None,
+                "Red",
+                "Blue",
+                "Green",
+                "Golden",
+                "Black",
+                "Fighting",
+                "Flying",
+            )
+        )
+        if adjective is None:
+            return animal.title()
+        return f"{adjective} {animal}".title()
+
+    def random_nickname(self) -> str:
+        while True:
+            nickname = self._make_random_nickname()
+            if nickname not in self.used_nicknames:
+                self.used_nicknames.add(nickname)
+                return nickname