smartctl_exporter already runs with SupplementaryGroups "disk", which
gives full access to SATA drives, but NVMe devices are owned by
root:root, resulting in no access:
[...] msg="Smartctl open device: /dev/nvme0 failed: Permission denied"
This patch introduces a "smartctl-exporter-access" supplementary
group, and an udev rule with setfacl to give the exporter access to NVMe
drives, without changing the base root:root ownership.
Fixes https://github.com/NixOS/nixpkgs/issues/210041
86a6ef5f15