Function setup_network_with 

pub async fn setup_network_with<'a, N: Netstack, I>(
    sandbox: &'a TestSandbox,
    name: &'a str,
    interface_config: InterfaceConfig<'a>,
    children: I,
) -> Result<(TestNetwork<'a>, TestRealm<'a>, TestInterface<'a>, TestFakeEndpoint<'a>)>
where
    I: IntoIterator,
    I::Item: Into<ChildDef>,

Sets up a realm with required services and a network used for tests requiring manual packet inspection and transmission.

Returns the network, realm, netstack client, interface (added to the netstack and up) and a fake endpoint used to read and write raw ethernet packets.