This renames/moves the following properties:
* sway_view.{x,y,width,height} ->
sway_container.content_{x,y,width,height}
* This is required to support placeholder containers as they don't
have a view.
* sway_container_state.view_{x,y,width,height} ->
sway_container_state.content_{x,y,width,height}
* To remain consistent with the above.
* sway_container_state.con_{x,y,width,height} ->
sway_container_state.{x,y,width,height}
* The con prefix was there to give it contrast from the view
properties, and is no longer useful.
The function container_set_geometry_from_floating_view has also been
renamed to container_set_geometry_from_content.
be9348d25c