feat: surfaces stick to a page id

[Julusian]

Follow up to #2689

Surfaces now track the page id, rather than page number.
This means that when reordering pages, they won't change what page is shown and instead redraw with the new topbar numbers.
The aim here is to allow users to insert and reorder pages freely, and not end up with streamdecks scattered onto random pages

TODO:

• Needs some more testing
• Needs to fixup the surface settings fields for old configs