Fix moving tiled containers to workspaces which only have floating views
Fix moving tiled containers to workspaces which only have floating views

* Make a workspace which only contains floating views
* Switch to another workspace and create a tiled view
* Move the tiled view to the workspace with
`move container to workspace N`

The container would be added as a sibling to the floating view, which
makes the container floating while having the geometry of a tiled
container.

This changes it so it only looks for tiled containers in the workspace
with a fallback to the workspace itself.

1ace/sway,ascent12/sway,ascent12/sway,ascent12/sway,1ace/sway,SirCmpwn/sway,1ace/sway