Expose data about 'first time' zone maintenance in-progress
Description
This relates to #3081 "When is BIND Ready". The operational need is to find a way to make BIND's status following a restart or reload, more accessible to operators of authoritative servers that host secondary zones (potentially also making use of catalog zones (CATZ) for management of the secondary zone list).
Request
In #3883 (closed) an enhancement is being made to provide information in the statistics channel regarding zone refreshes that are queued or in-progress.
Per !7984 (comment 391140) , this is a request to implement a per-zone flag that is set when a server is started or reloaded, against secondary zones that cannot be 'trusted' to be up to date until their first refresh has completed.
The 'first time' flag also needs to be propagated from the 'first time' refresh of a secondary catalog zone to all zones that it adds to the zone table during start-up.
With this additional information, it should be possible to report separately to the table already being produced per !7984 (merged) a list or table of zones that still have their 'first time' refresh queued or currently in-progress.
Noting also that there's a count of zones being refreshed currently in the output of 'rndc status', it should similarly be possible to create a similar count of 'first time' zone refreshes.