Fixed the music button on the main menu not working

[Thompson6626]

👉 Checklist

Please make sure to check off the following before submitting:

• [✅] I have reviewed my submission thoroughly.
• [✅] I have tested my code (if submission is related to coding) and run the game before pushing (to make sure the project compile).
• [✅] I have run the JUnit tests (if submission is related to coding).
• [✅] I have read the Code of Conduct and Contribution Guidelines.

✍ Description of the Pull Request

Please concisely describe the changes you have made. I've fixed the following issues:

• Fixed an issue where the music button did not turn music back on after being turned off.
• Fixed a bug where the background music from the game wouldn't stop when returning to the main menu.
• Added a playing music image to differentiate between muted and unmuted states.

🔗 Issue link

Issue reference number and link goes here e.g. 'Fixes/Closes #<issue_number>'.

• [✅] This Pull Request fixes the issue : 'Closes #106'
• [ ] This Pull Request does not fix an issue.

Thanks for taking the time to fill out this Pull Request! ❤️ Thanks for contributing to this project 🦖