Fixed all issues (1-6) and completed enhancements

[vedant208purohit]

This pull request resolves all outstanding issues for the project.

• Closes Increase difficulty level as the game proceeds. #1: Increased difficulty level as the game proceeds.
• Closes Food should not spawn inside snakes body #2: Ensured food does not spawn inside the snake's body.
• Closes Maintain and update score as the game proceeds #3: Maintained and updated the score as the game proceeds.
• Closes Spawn poisonous food that snakes needs to avoid. #4: Spawned poisonous food that the snake needs to avoid.
• Closes Add play/pause functinality in the game #5: Added play/pause functionality to the game.
• Closes Keep track of top 10 highest scores #6: Kept track of the top 10 highest scores.