This isn't the grouped layer control that we have in the non-react map.
The react variant of that hasn't been updated in years and won't work
with our base maps (and may not work at all). We'll need to fix that or
write our own if we want to use that. This will do for now though.
https://github.com/dcs-liberation/dcs_liberation/issues/2039
There was accidentally a second layer of callback here. I'm not sure why
it worked. I think the lambda being returned was being used as the
cleanup function?
