mod_restrict_xmpp: Treat archive query as a read despite using iq-set XEP-0313 uses iq-set to initiate a query, but unlike many other uses of iq-set, this does not mutate anything on the server, so it should not be treated as a write request.

This module lets you block connections to any remote servers not on a
whitelist.

``` {.lua}
s2s_whitelist = {
    "example.org",
}
```