[Feature request] Allow overriding the enabled_policies configuration via a command-line option

In Kicksecure, we currently offer users the ability to use extrepo as part of a procedure for converting an existing Debian 13 installation to a Kicksecure 18 installation. This makes it significantly easier to add Kicksecure's repos to a device in a safe manner, as extrepo handles things like verifying signing keys for the user. It also mostly avoids the need for the user to modify configuration files.

However, there is the issue of /etc/extrepo/config.yaml. This file by default disables the contrib and non-free pockets of third-party repositories, which is a reasonable default but also breaks the ability for users to install the non-free firmware metapackages we ship in our repo (firmware-nonfreedom and firmware-nonfreedom-network). None of the packages in Kicksecure are themselves non-free software, but we place these metapackages in the non-free pocket because they have dependencies on non-free firmware and always will.

All of our documentation instructs the user to enable the main, contrib, and non-free pockets of our repo when manually adding repos, so this means that the user now has to edit extrepo's configuration in order to do this. Not only is this non-ideal from a UX standpoint, it also means that the user now has the contrib and non-free pockets enabled in extrepo in general, which could result in them installing other non-free software from other repositories. Avoiding that requires telling the user "if you aren't using non-free software, edit this file and disable these two lines again, otherwise leave them enabled". This hampers usability quite a bit.

It would be very useful if there was an option like --with-pocket=XYZ, which could be specified multiple times. XYZ could be contrib, non-free, etc. Then we could tell users to use something like sudo extrepo enable --with-pocket=contrib --with-pocket=non-free kicksecure. Those options would augment the enabled_policies configuration only for the current run, so the user would get all of the repos without having to persistently enable non-free repos.

If this is something the extrepo team would be willing to accept, I may be able to file an MR implementing this.