placementtracker: fix some windows not being restored

If a window was moved by the user, it got effectively blacklisted from being ever restored again (unless the output it was on got removed). Instead of tracking the last restore point, always compare the current window state with the state it had when the output configuration was last seen

Draft not because it's incomplete, but because I'm fairly certain there was a reason I didn't do it this way from the get go. So some testing on different setups would be good.