Instead of having to manually stub packages that should not be
downloaded we instead automatically stub all packages (except a small
list of whitelisted ones). Tests can re-introduce the real package by
using the `realPkgs` module argument.
Adding unmailboxes option to neomutt, which adds the `unmailboxes`
option it to every account.email with neomutt enabled.
See https://www.mutt.org/doc/manual/#mailboxes for more.