adwaita-icon-theme: recolor folder icons

[danth]

Issues:

• base02 and base01 are used since this needs two shades of the same color. It should really be using base0D since the original icons were blue, but then we don't have a lighter shade for the icon and the tab at the top.
• This causes every package related to GNOME to be compiled from source. It's possible to work around this by placing the icon theme directly into environment.systemPackages with meta.priority set to override the original scheme. However, this is difficult to implement in Stylix since doing that would install the icon theme when it's not needed.