hostname: add hardware family, sku and version (#36956)

Add support for the hardware family, SKU (Stock-Keeping Unit) and
version. The values are read from the file /etc/machine-info or DMI as
fallback.

The entries are useful to provide an unified interface to collect detail
hardware information. The /etc/machine-info entries enable embedded
devices without UEFI support to provide the information via a common
interface.

Fixes: #31134

diff --cc src/hostname/hostnamectl.c
Simple merge