Finish implementation of add/remove squadrons from AirWingConfigurationDialog

Users can now add and remove squadrons with specific buttons. this also allows new aircraft types to be added as well.

- rebased existing PR to develop
- reverted observable and changed to signals
- changed the general concept so that changes only affect the ui data model and not the game directly. Game will only be updated on apply
- removed unused code
- adopt to review comments
- allow user to choose a predefined squadron preset (also alow none value to use the random generator)
- Reuse the squadron defs from the default assigner in the AirWing class
- allow user to re-roll the squadron nickname (also added new ui icons for the button)

game/squadrons/squadron.py

@@ -418,6 +418,7 @@ class Squadron:
         coalition: Coalition,
         game: Game,
     ) -> Squadron:
+        squadron_def.claimed = True
         return Squadron(
             squadron_def.name,
             squadron_def.nickname,