This deprecates IPForward= setting, which unconditionally controled
the global setting, even though it is a setting in .network file.
Instead, this introduces new IPv4Forwarding= and IPv6Forwarding=
settings both in .network and networkd.conf.
If these settings are specified in a .network file, then the
per-interface forwarding setting will be configured.
If specified in networkd.conf, then the global IP forwarding setting will
be configured.
Closes#30648.
Those are all consumed by our parser, so they all support comments.
I was considering whether they should have a license header at all,
but in the end I decided to add it because those files are often created
by copying parts of real unit files. And if the real ones have a license,
then those might as well. It's easier to add it than to make an exception.
Yu Watanabe
Zbigniew Jędrzejewski-Szmek