filter-aaaa can be used as zone or view plugin

filter-aaaa can be used as zone or view plugin

Update the filter-aaaa system test so the two authoritative zones
in ns4 both configure filter-aaaa as a zone plugin.

In order to work in both contexts, the plugin must register both
the `NS_QUERY_QCTX_INITIALIZED` and `NS_QUERY_AUTHZONE_ATTACHED`
hooks.

When the plugin is configured at the zone level in an authoritative
server, `NS_QUERY_QCTX_INITIALIZED` is skipped, because no zone will
have been looked up by the time it is called.  When the zone is
found, calling `NS_QUERY_AUTHZONE_ATTACHED` will allow the same
initialization to occur.