Separate combat as a distinct flight state.

Will be used later to simulate combat.

https://github.com/dcs-liberation/dcs_liberation/issues/1680

game/ato/flightstate/incombat.py

@@ -0,0 +1,56 @@
+from __future__ import annotations
+
+from datetime import datetime, timedelta
+from typing import TYPE_CHECKING
+
+from dcs import Point
+
+from game.utils import Distance, Speed
+from .inflight import InFlight
+from ..starttype import StartType
+
+if TYPE_CHECKING:
+    from game.sim.aircraftengagementzones import AircraftEngagementZones
+
+
+class InCombat(InFlight):
+    def __init__(self, previous_state: InFlight, description: str) -> None:
+        super().__init__(
+            previous_state.flight,
+            previous_state.settings,
+            previous_state.waypoint_index,
+        )
+        self.previous_state = previous_state
+        self._description = description
+
+    def estimate_position(self) -> Point:
+        return self.previous_state.estimate_position()
+
+    def estimate_altitude(self) -> tuple[Distance, str]:
+        return self.previous_state.estimate_altitude()
+
+    def estimate_speed(self) -> Speed:
+        return self.previous_state.estimate_speed()
+
+    def on_game_tick(self, time: datetime, duration: timedelta) -> None:
+        raise RuntimeError("Cannot simulate combat")
+
+    @property
+    def is_waiting_for_start(self) -> bool:
+        return False
+
+    def should_halt_sim(self) -> bool:
+        return True
+
+    def check_for_combat(
+        self, enemy_aircraft_coverage: AircraftEngagementZones
+    ) -> None:
+        pass
+
+    @property
+    def spawn_type(self) -> StartType:
+        return StartType.IN_FLIGHT
+
+    @property
+    def description(self) -> str:
+        return self._description