Consider consolidating BNetworkServiceSettings to launch daemon

[kallisti5]

the net_server currently has a BNetworkServiceSettings class to handle inetd-style forking of network services (our sshd currently uses it)

However, it was pointed out in IRC that launch daemon might be a better place for this.

Considerations:

• net_server is likely not the most secure place to be forking processes.
• launch_daemon is already well designed, and could have a new type added for "inetd services"

Design Considerations:

• net_server could do basic firewalling of ports, and notify launch daemon of unhandled inbound requests.
• launch daemon could then "decide" if it wants to do anything with the network request, or drop it.

Pros:

• launch daemon managing inetd services would put full control and inventory of services in one place.
• launch daemon could adjust inetd services based on varying targets.
• services could "self-register" inetd with launch daemon by dropping a new launch script. (openssh drops a disabled inetd service off with launch daemon which waits on network)
• Today, ssh is hardcoded in our Network Preflet add-on.
• CLI management of inetd style services through launch_roster
• GUI management of inetd style services via X512's launch daemon gui tool.

Cons:

• It's kind of a shuffle of code
• Our use case doesn't need "targets" for inetd services

[kallisti5]

See #14086 for where this conversation spawned.

[kallisti5]

example:

target desktop {
    netservice x-vnd.sshd {
        port 22/tcp                                                                         
        launch /bin/sshd -D
        on network_available
    }
}

We may want to rename "service" to "daemon" within launch dameon if this is something we want to consider.

[kallisti5]

Context / example for SSH today:

• src/add-ons/network_settings/sshd/SSHServiceAddOn.cpp: BNetworkServiceSettings settings;
• src/kits/network/libnetapi/NetworkSettings.cpp:BNetworkServiceSettings
• src/kits/network/libnetapi/NetworkSettings.cpp: return BNetworkServiceSettings(service);
• src/kits/network/libnetapi/NetworkSettings.cpp:const BNetworkServiceSettings