This fixes a crash in `container_init_floating` when a xwayland view
sends a configure request while in the scratchpad.
`container_init_floating` gets called so the configured minimum and
maximum sizes gets respected when resizing to the requested size. Since
the workspace was NULL, it would SIGSEGV when attempting to get the
workspace's output for the output box retrieval.
This extracts the resizing portion of `container_init_floating` into a
separate function. If the container is in the scratchpad, it will just
be resized and skip the centering.
Additionally, `container_init_floating` has been renamed to
`container_floating_resize_and_center` to more accurately describe what
it does.
dd28e6a6d6