policy and statistics: improvements?

• UX. Each rule in the list of policies has a .count, but it's not much useful as it is. It's not exported in usual statistics and introspecting by hand makes it hard to read the list.

[rules] => {
    [1] => {
        [count] => 40698
        [id] => 0
        [cb] => function: 0xb69374b0
    }
}

Consider collecting more statistics:

• RPZ rules might additionally collect a counter of matches for each RPZ file line. That seems relatively cheap on performance side, but it's difficult in the way the abstractions are done now, as the [cb] (above) knows nothing about the "parent table".
• Count of "secure" answer would be interesting, i.e. those that would set AD flag if requested. (ATM the state isn't well visible unless the request had DO or AD.)
• e.g. inspiration https://pi-hole.net