Site fixes

I added support for nested folders, plus some groundwork for supporting forms (so far only forms that don't exist are supported). See https://codeberg.org/JacobK/hydrilla-fixes-bundle/commit/57cc623b6b9a135c58379bed97f9fc5ec05dfbd2

I have lightly tested this on a clean Abrowser profile using haketilo/hydrilla/hydrilla-builder 3.0b1.

Here's some example URLs that work properly with this code:

https://app.box.com/v/b00ks
https://app.box.com/v/b00ks/folder/26616236521
https://app.box.com/v/b00ks/folder/47804220915 (This one also works with the old JavaScript, but you need the new index.json)
https://dronepadmedia.app.box.com/f/a14b5488396345c3ab0466d805636b83 (supposed to be not found as the form has expired I think)

(side note: It seems that Box forms are pretty uncommon. There seems to be only one example on Reddit ever: https://old.reddit.com/search/?q=url%3A%22app.box.com%2Ff%22&sort=new&restrict_sr=&t=all)