Add the ability to get events whenever a flaoting window moves including the window's new x,y cords in sway-ipc

[Zai-Kun]

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• We are not accepting any new window management features unless they get implemented by i3.

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• Description:
  The title is pretty self-explanatory. It would be really nice if the client could subscribe to events when a floating window is moved. By moving a floating window, I mean when the user moves the window by pressing the mod key, holding the left click, and moving it around.

(I really need this feature for the tool I'm creating)