auth: factor code responsible for the NSEC{,3} QType bitmap computation

[miodvallat]

Short description

There are two large blocks of code computing NSEC and NSEC3 record type bitmap values, with subtle differences between them.

This PR factors the two large common parts, which makes the distinction between NSEC and NSEC3 processing more visible.

There are absolutely no functional changes intended. However I forgot to switch the Kärcher™ off and got side-tracked with minor extra changes:

• removal of dead code in DNSPacket
• since an early version of that PR horribly broke the *-*-both tests because of missing domain_id field assignments and confused the record signing code, I have added, for records which are synthesized, either explicit assigment of that field when the proper value is known, or an annotation that the value remains the default value.

Checklist

I have:

• read the CONTRIBUTING.md document
• read and accepted the Developer Certificate of Origin document, including the AI Policy, and added a "Signed-off-by" to my commits
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[coveralls]

Pull Request Test Coverage Report for Build 22138865234

Details

• 78 of 82 (95.12%) changed or added relevant lines in 1 file are covered.
• 96 unchanged lines in 12 files lost coverage.
• Overall coverage decreased (-0.01%) to 71.605%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pdns/packethandler.cc	78	82	95.12%

Files with Coverage Reduction	New Missed Lines	%
pdns/misc.cc	2	62.07%
pdns/recursordist/aggressive_nsec.cc	2	66.54%
pdns/recursordist/rec-main.cc	2	64.88%
pdns/fstrm_logger.cc	3	58.57%
pdns/recursordist/taskqueue.hh	3	85.71%
pdns/remote_logger.cc	3	58.12%
pdns/recursordist/pdns_recursor.cc	4	75.55%
pdns/packethandler.cc	5	72.33%
pdns/tcpiohandler.cc	9	60.16%
pdns/recursordist/syncres.cc	13	81.24%

Totals
Change from base Build 22132718412:	-0.01%
Covered Lines:	129693
Relevant Lines:	166086

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💛 - Coveralls