Add cursed apple: a status-effect apple that inverts controls

Eating a cursed apple inverts the snake's steering for
CURSE_DURATION_TICKS ticks, shown on the top screen while active. The
sprite is a recolored copy of the rotten-apple tile since all existing
sprite tiles are already in use.

include/game_logic.h

@@ -7,7 +7,10 @@ void update_snake(GameState &state);
 bool check_collision_self(GameState &state);
 bool check_collision_apples(GameState &state);
 bool check_collision_apples_rotten(GameState &state);
+bool check_collision_apples_cursed(GameState &state);
 void spawn_apples(GameState &state);
 void spawn_apples_rotten(GameState &state);
+void spawn_apples_cursed(GameState &state);
+void tick_status_effects(GameState &state);
 
 #endif