RFC: consider read only sysctl errors as non fatal

When running inside of unprivileged containers /proc is normally mounted read only.
Now if a users tries to run netavark it will fail hard if we cannot set all the sysctl's. Most of them are needed for routing or to disable some ipv6 options but general communication may still be possible.

We should consider not treating read only errors as fatal and just log them as warning. The biggest problem is likely the ip_forward sysctl, without it no external communication would be possible. However this could already be set by the outer container manager in which case I would expect it to mostly work fine.

see https://github.com/containers/podman/issues/19991