This fixes the following. Create these layouts and run move right:
(Initial layout -> expected result -> actual result)
* `H[S[unfocused focused] unfocused]` ->
`H[S[unfocused] focused unfocused]` ->
`H[H[S[unfocused] focused] unfocused]`
* `H[S[unfocused focused] V[unfocused]]` ->
`H[S[unfocused] V[unfocused focused]]` ->
`H[H[S[unfocused] focused] V[unfocused]]`
move_out_of_tabs_stacks was originally made to allow views to move out
of the tabbed/stacked container in the parallel direction, but at some
point this has started working using the regular logic.
93624599b3