Replace 🏰 BuidlGuidl with the BuidlGuidl logo

[ZakGriffith]

Since we have clean logos now, it would be nice to update the footer BuidlGuidl wording from 🏰 BuidlGuidl to the actual logo. We hav both light and dark modes available so that would need to be implemented as well. The logo files can be found in this Figma:
https://www.figma.com/file/jPaXdmHNfbTSwBWwENr6Iq/BG-Media-Kit?type=design&node-id=0-1&mode=design&t=mvJiUwXPXhZ7LQaz-0

[FilipHarald]

I can give this a try. Should I create an issue then?

[FilipHarald]

If I understand the Contributing-docs correctly an issue is only needed for larger PRs. I gave it a shot here. I don't know if the CSS is optimal, but maybe I will get feedback on that in PR.

[carletex]

Fixed on #551