net.list() ignores multiple ports on the same IP address

Multiple invocations of net.listen() using the same IP address but different port will confuse output of net.list(). Only single endpoint description listening for a given IP address is returned by net.list:

Example:

$ KRESD_NO_LISTEN=1 kresd
> net.list() 

> net.listen('::1', 5353)
true

> net.list()
[::1] => {
    [tcp] => true
    [tls] => false
    [udp] => true
    [port] => 5353
}

> net.listen('::1', 53000)
true

> net.list()
[::1] => {
    [tcp] => true
    [tls] => false
    [udp] => true
    [port] => 5353
}

Fixing this obviously requires change to net.list() output format, which can be done in upcoming 4.0.

The main question is how the new output should look like. Preliminary proposal: { address = 'string', transport = udp/tcp/quic, transport_params = { [transport-dependent parameters - port etc.] }, security = tls/dtls/..., format = plain DNS/DNS-over-HTTP-binary/DNS-over-HTTP-JSON }

net.list() would then produce numbered list of tuples, each tuple describing single combination.

While this would be technically correct I don't know if it would be too verbose and ugly. Maybe we should introduce net.summary() which could produce a nicer output out of net.list() or something like that.