floating restore - restore the floating state a window had on launch

[LordGrimmauld]

Description:
Sway knows whether a container should launch floating or docked using for_window rules. Once launched, floating can be enabled, disabled, or toggled. It is however not possible to restore the floating state that was assigned at launch of the container. I therefore propose a floating restore option to restore whatever was defined in window rules. This would be especially helpful to restore sane presets when restoring from scratchpad instead of having everything just be floating.
I understand this is not directly a feature within i3 without a seperate daemon process keeping track about what a certain container was started as. If this doesn't end up a valid feature request, i'll likely see if i can get a patch or even pr in swayfx going, just figured i'd go upstream first.