Break lock order loop by sending TAT in an event

Break lock order loop by sending TAT in an event

The dotat() function has been changed to send the TAT
query asynchronously, so there's no lock order loop
because we initialize the data first and then we schedule
the TAT send to happen asynchronously.

This breaks following lock-order loops:

zone->lock (dns_zone_setviewcommit) while holding view->lock
(dns_view_setviewcommit)

keytable->lock (dns_keytable_find) while holding zone->lock
(zone_asyncload)

view->lock (dns_view_findzonecut) while holding keytable->lock
(dns_keytable_forall)

(cherry picked from commit 3c4b68af7c0cd8213bcae92faee3bf2a7e9284d1)