BIND 10 #3115: Migrate loadzone to notification

[BIND 10 Development]

#3115: Migrate loadzone to notification
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                   Reporter:         |                 Owner:
  vorner                             |                Status:  new
                       Type:  task   |             Milestone:  Next-Sprint-
                   Priority:         |  Proposed
  medium                             |              Keywords:
                  Component:         |             Sensitive:  0
  Unclassified                       |           Sub-Project:  DNS
               CVSS Scoring:         |  Estimated Difficulty:  0
            Defect Severity:  N/A    |           Total Hours:  0
Feature Depending on Ticket:         |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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 Currently, several our daemons act when new zone data is available (Auth
 to reload, XfrOut to send notifications, possibly more and we need to add
 the MemoryManager there too). Each of them currently exposes a loadzone
 command. Several components produce zone data (XfrIn, DDNS) and each of
 them explicitly calls the command on each of the consuming components.
 This is obviously wrong.

 So, in this task, we migrate this to MsgQ notifications.

 Decide:
  * Name of the notification group (suggested: ZoneData)
  * Name of the event (suggested: ZoneChanged) and its parameters (probably
 the same as the parameters of current LoadZone commands ‒ name of data
 source, origin of zone, zone class).

 Move the consumers to subscribe to the notification group and act upon the
 event (simply call the same code as for the LoadZone command internally).
 Remove the LoadZone command.

 Let the XfrIn and DDNS produce event instead of calling the direct
 commands.

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Ticket URL: <http://bind10.isc.org/ticket/3115>
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BIND 10 Development