Show photo page of image behind topo

[quaestor]

What happened?

There is no way to show the original image behind a topo. This would sometimes be useful to add new routes, because in the small version shown in the topo editor, you sometimes cannot see enough details to spot where the new line is (e.g. bolts, pockets). If you didn't create the topo yourself, you might not have another reference picture. This also relates to #2353, because uploading your own photo (so you have a full-size reference) is cumbersome, as you need to redraw all the routes, even if you might have a picture from a similar angle.

What you expected:

Add a button to the topo dropdown to show the full-size photo.