Add portmappings to ContainerCreateOptsBuilder

[marhkb]

What did you implement:

While working on this PR I saw that there is a TODO for portmappings in ContainerCreateOptsBuilder, which I need. Thus, I implemented it.

How did you verify your change

I tested this within the PR.

The code I use is basically:

//...
.portmappings(
    imp.port_mappings
        .borrow()
        .to_owned()
        .to_typed_list_model::<model::PortMapping>()
        .into_iter()
        .map(|port_mapping| api::PortMapping {
            container_port: Some(port_mapping.container_port() as i64),
            host_ip: None,
            host_port: Some(port_mapping.host_port() as i64),
            protocol: Some(port_mapping.protocol().to_string()),
            range: None,
        }),
)
//...

The portmappings are accepted and are shown in cockpit.

What (if anything) would need to be called out in the CHANGELOG for the next release

Probably the titles of both commits would fit here.

[vv9k]

Looks good to me! Thank you :)