When moving a workspace to the current output by way of a rename, if the
current workspace is empty, it will be removed by `workspace_show`.
Attempting to restore focus to this removed workspace causes a crash.
Follow the pattern in workspace.c:996 to only restore the original focus if the
original workspace still exists.
Add a test to ensure that the renamed workspace moves to its appropriate
output and that a crash does not occur.
Fixes#3228
Currently when renaming outputs, an output assignment of "left" will
cause the workspace to move left. Treat this assignment as a proper name
instead (even though it is unlikely an output will be named "left").
Move logic for determining output to move to out of
`workspace_move_to_output`
Add test for ignoring direcionality during rename.
Fixes#3208.
Orestis Floros