Migrates from the deprecated toCommandLine to toCommandLineGNU.
This changes the output format to use GNU-style options with equals
(--wheel-lines=3). Both formats were verified to work correctly with less.
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.
