AI unlimited fuel initial implementation (#227)

* Unlimited fuel for AI flights. For player flights, included at startup, for AI flights with join/split, applied at join/split.

* Unlimited fuel for AI flights. For player flights, included at startup, for AI flights with join/split, applied at join/split.

* Corrected default value of ai_unlimited_fuel to False in configure_behavior

* ai_unlimited_fuel : set argument based on setting and simplify activation section

* AI Unlimited Fuel : enable at start, disable at racetrack start/join, enable at racetrack end/split

* Correct typing : bool to Optional[bool]

---------

Co-authored-by: tmz42 <thomas.monnzie@gmail.com>

game/settings/settings.py

@@ -822,6 +822,16 @@ class Settings:
         ),
     )
 
+    ai_unlimited_fuel: bool = boolean_option(
+        "AI flights have unlimited fuel",
+        MISSION_GENERATOR_PAGE,
+        GAMEPLAY_SECTION,
+        default=True,
+        detail=(
+            "AI aircraft have unlimited fuel applied at start, removed at join/racetrack start, and reapplied at split/racetrack end for applicable flights. "
+        ),
+    )
+
     # Performance
     perf_smoke_gen: bool = boolean_option(
         "Smoke visual effect on the front line",