[Quadlet]: Add support for --sysctl

[LauKr]

Feature request description

As far as I saw there is no support for the --sysctl flag up to now for Quadlet.
When using --sysctl for a container, this, at least to my understanding, makes it impossible to simultaneously use Quadlet.

Suggest potential solution

I think this can easily be done similar to other options, like e.g. AddCapability in quadlet.go, something like:

	addSysctl := container.LookupAllStrv(ContainerGroup, KeyAddSysctl)
	for _, sysctl := range addSysctl {
		podman.addf("--sysctl=%s", strings.ToLower(sysctl))
	}

As this is neither tested yet nor I'm fluent in Go, please take with a grain of salt. Also, I'm not sure if the input should be filtered for allowed entries based on namespaces, or if Podman throwing the corresponding error is enough.

Have you considered any alternatives?

One could always use the podman generate command to generate a separate unit file based on the used container, but mixing different types of container administration is not ideal.

Additional context

No response

[Luap99]

You can use PodmanArgs= to set arbitrary podman args that are not directly exposed in quadlet.
In any case this sounds like a reasonable request to support it directly in quadlet.

[rhatdan]

I agree.

[LauKr]

I gave the implementation a try.
For me it works, I can use the AddSysctl flag with one or several entries and they will be passed to the container as expected.