UI: allow creating pages via Common Lisp based virtual DSL

[mdbergmann]

Can create multiple pages that allow multiple layers of elements. I.e:

• a house floor based page like that allows to specify floors, rooms in floors and items in rooms.

or a

• functional based page setup that specified lights, plugs, and other thing

It doesn't need to be multiple layers, but the last layer must be the item.

And probably we have a max of three layers where we have page (house), tabs (floors), cards (rooms), elements in cards (items)