Time for action – accepting user input

To add support for handling user input to the MarsRunnerPlayScreen class, perform the following steps:

1. 1. In the Fields region of the MarsRunnerPlayScreen class, add two new fields to track the player's desired movement direction and the base movement speed as follows:

   int moveState = 0;
   int moveSpeed = 8;

2. 2. Add the HandleInput() override method to the MarsRunnerPlayScreen class as follows:

   #region Handle Input
   public override void HandleInput(InputState input)
   {
       moveState = 0;
       if (
           (input.CurrentKeyboardStates[0].IsKeyDown(Keys.Left)) ||
           (input.CurrentGamePadStates[0].ThumbSticks.Left.X < -0.3f)
           )
       {
           moveState = 1;
       }
   
       if (
           (input.CurrentKeyboardStates[0].IsKeyDown(Keys.Right)) ||
           (input.CurrentGamePadStates[0].ThumbSticks.Left.X > 0.3f)
           )
       {
           moveState = 2;
       }
   
       if (
           (input.CurrentKeyboardStates[0].IsKeyDown(Keys.Up)) ||
           (input.CurrentGamePadStates...