feat: first basic enemy patrolling behaviour

modules/wave_survival/npc_unit.h

@@ -0,0 +1,31 @@
+#ifndef NPC_UNIT_H
+#define NPC_UNIT_H
+
+#include "scene/main/node.h"
+class StateMachine;
+class EnemyBody;
+class PatrolPath;
+
+class NpcUnit : public Node {
+	GDCLASS(NpcUnit, Node);
+	static void _bind_methods();
+	void child_added(Node *node);
+	void enter_tree();
+
+protected:
+	void _notification(int what);
+
+public:
+	void set_patrol_path(PatrolPath *path);
+	PatrolPath *get_patrol_path() const;
+	bool is_aware_of_player() const; //!< becomes true when any individual in the unit sees the player.
+	void set_patrol_speed(float value);
+	float get_patrol_speed() const;
+
+private:
+	Vector<EnemyBody *> npcs{};
+	PatrolPath *patrol_path{ nullptr };
+	float patrol_speed{ 3.f };
+};
+
+#endif // !NPC_UNIT_H