Feature/menu improvements

[swiimii]

Description

16 Added a non-Arial font to menus, and added functioning Master, Music, and SFX sliders to settings.

How Has This Been Tested?

While there are no sounds in game yet, I've tested that the sliders will successfully change the value of the Audio Mixer (located in Assets > Audio > Mixer.

To confirm that these changes work, you can double-click the Mixer in the Project view, play the scene, navigate to the settings menu, change the values of the sliders, and watch the effects made on the Audio Mixer the 'Audio Mixer' window.

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings

[swiimii]

Accomplished using this tutorial: https://www.youtube.com/watch?v=xNHSGMKtlv4