Enable support for running Docker container on Arch Linux and derivative hosts

[Church13]

In Arch Linux and derivatives, the cdrom group does not exist. Access to interfacing with disc drives is done through the optical user group which has the GID 990. This PR creates such an optical user group in the container and adds the arm user to that group.

This enables support for running ARM on hosts which are running Arch Linux or derivatives, like Manjaro.

Adding the group has the remote potential to alter the security posture for running the container, only if it is running on a system where being a member of the group with the GID 990 maps to a group in the host system other than the optical group. However, this is a very low risk.

Link to successful PR build run: https://github.com/Church13/arm-dependencies/actions/runs/12101157198/job/33740661866?pr=4

[mihawk90]

Isn't this something the user can take care of by simply supplying an ARM_UID and/or ARM_GID that has the appropriate accces rights?

[microtechno9000]

Isn't this something the user can take care of by simply supplying an ARM_UID and/or ARM_GID that has the appropriate accces rights?

Yes, that should work. I like the idea of making it easier for users out the box.

Confirming Arch uses optical
https://wiki.archlinux.org/title/Users_and_groups