Fix tracking of geometry restore with electric maximize

If the user wants to move a tiled window, but changes their mind and tiles the window back to the previous position, the geometryRestore() will be corrupted because initialMoveResizeGeometry() is the same as the geometry of the window in the tiled mode.

This change fixes tracking of the geometry restore by precomputing the geometry restore when starting interactive move. That way, if the window is untiled and tiled again without release left pointer button, the geometry restore will be set to the correct value in setQuickTileMode().

This change also adjusts the test suite so such a subtle case won't be broken again without noticing it.