Currently, finishInteractiveMoveResize() relies on a hidden behavior
in the sendToOutput() function that makes it treat fullscreen windows
differently, which is confusing.

With this change, finishInteractiveMoveResize() will use the
checkWorkspacePosition() function to make sure that the geometry of the
fullscreen window is adjusted to the new monitor. It allows to make
sendToOutput() more straightforward.

It also fixes checkWorkspacePosition() using wrong geometry type in the
fullscreen window path.