Don't require cockpit-ws if possible

[erazemk]

Bug Info

Describe the bug
On Fedora CoreOS (or IoT) systems, the procedure to install Cockpit is a bit different than on normal non-rpm-ostree systems. To be able to run the webserver on the same device, cockpit-ws has to be run in a podman container. If installing cockpit-identities on such systems, the podman parts will fail, as they require that cockpit-ws is not installed on the host system.

More info about the installation procedure: https://cockpit-project.org/running.html#coreos

To Reproduce
Steps to reproduce the behavior:

1. Follow the official guide for installing Cockpit on CoreOS
2. Additionally install cockpit-identities
3. Fail on running the cockpit-ws container, because cockpit-ws is already installed on the host system

Expected behavior
cockpit-ws is not a required dependency.

Server Side

• OS: Fedora IoT 38
• Cockpit Version: 250.1.1