Move actions from the "win" namespace to the "doc" namespace
Summary
Actions apply to the whole window, even when they don't really make sense
Description
This is some legacy from Evince and GTK3. We started fixing it in !155 (merged), but as mentioned in !155 (comment 2082824), we should continue. Every action should be moved to the doc except:
win.open
win.close
win.fullscreen
win.escape
win.show-side-pane
win.inverted-colors
In addition, we should make sure that we add the actions to the correct widget, and not to the window