Add support for systemctl reload with quadlets

[mordae]

Feature request description

I have a running haproxy.container. systemctl reload haproxy responds with:

Failed to reload haproxy.service: Job type reload is not applicable for unit haproxy.service.

Suggest potential solution

Would it be possible to:

1. Support e.g. ReloadSignal=HUP syntax in the .container files?
2. Translate them to ExecReload=podman kill --signal=HUP systemd-haproxy?

Have you considered any alternatives?

One can currently run podman kill --signal=HUP systemd-haproxy directly, but that's hardly ergonomic. With proper reload support other tools such as cockpit would pick up on that and provide the option (in the service management tab at least). It is also easier to teach reload to newcomers than tell them to use kill to reload configuration.

Additional context

No response