Add a "Revert to Original Style" button for UI Customisation.

For neurodivergents, it can be extremely difficult to get used to new changes for something that has stayed the same way for many years. Although I can understand why the new Discord customisation styles have been brought in, I fail to see why the original style for buttons, messaging layouts, channel profile images, and panel colours etc. have been completely taken away. 

It seems unreasonable to introduce new customisation features but not allow you to customise back to how it used to look. I'm proposing a simple button to revert these changes to allow people who preferred the older style for Discord to go back to that original look.