[FEATURE REQUEST] Add USRBG Support

[USRBG](https://github.com/Discord-Custom-Covers/usrbg) is a custom database for hosting user banners for those using BetterDicord who don't have the beta feature. It would be great if this feature would be implemented into this theme, so people can see each others custom user banners from this database. There is absolutely no pressure, so take your time. Thanks.