BIND 10 #2676: Provide ccsession::rpc_call and replace usual calls with it

[BIND 10 Development]

#2676: Provide ccsession::rpc_call and replace usual calls with it
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                   Reporter:         |                 Owner:
  vorner                             |                Status:  new
                       Type:         |             Milestone:  Next-Sprint-
  enhancement                        |  Proposed
                   Priority:         |              Keywords:
  medium                             |             Sensitive:  0
                  Component:         |           Sub-Project:  Core
  Inter-module communication         |  Estimated Difficulty:  0
               CVSS Scoring:         |           Total Hours:  0
            Defect Severity:  N/A    |
Feature Depending on Ticket:         |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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 Provide a simple wrapper around building a command message, sending it
 with `group_sendmsg` (with `want_answer = True`) and receiving the answer
 with `group_recvmsg`.

 It should return the returned value, or raise some new exception when an
 error is returned (mostly for convenience of use).

 Then use this method to replace the usual calls to RPC by `group_sendmsg`
 and `group_recvmsg`. After that, the timeout for waiting for answer can be
 raised, since the timeouts should no longer happen due to the other side
 not existing.

 This is continuation of #1924.

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Ticket URL: <https://bind10.isc.org/ticket/2676>
BIND 10 Development <http://bind10.isc.org>
BIND 10 Development