Add player controller, state management, and input handling

- Implemented PlayerController.cs to manage player movement and actions.
- Created PlayerState.cs to track player lives, coins, and key status.
- Added CameraFollow.cs for smooth camera movement following the player.
- Developed Character.cs as an abstract class for character behavior.
- Introduced Enums.cs for defining TreasureType and MapElementType.
- Added IDoor interface for door interactions.
- Created InputActions.cs for handling player input actions.
- Implemented MainMenu.cs for basic menu functionality including play and exit options.

Assets/Scripts/Utilities/MainMenu.cs

@@ -0,0 +1,17 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+using UnityEngine.SceneManagement;
+
+public class MainMenu : MonoBehaviour
+{
+    public void Play()
+    {
+        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex+1);
+    }
+
+    public void Exit()
+    {
+        Application.Quit();
+    }
+}