Replace use of whitelist with allowlist and blacklist with denylist

I am reading and working with Box API and I have noticed that they refer to blocklist as blacklist and allowlist as whitelist.

Considering a lot of argumentations, besides that those words are racists and we can't even use it as a verb.

Some discussions: https://twitter.com/dhh/status/1032050325513940992.

I think that Box could also follow the good exemples and replace theses terms.

Also:

> Regardless of origin, allow/deny are simply clearer terms that does not require tracing the history of black/white as representations of that meaning. We can simply use the meaning directly.
>
> _Originally posted by @dhh in https://github.com/rails/rails/issues/33677#issuecomment-414873738_