Replace deprecated lib.cli.toGNUCommandLine with lib.cli.toCommandLineGNU.
Should support the GNU style of convention.
Signed-off-by: Austin Horstman <khaneliman12@gmail.com>
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.
