Recursor: Add more, empty Special Use domains

[pieterlexis]

Short description

This PR adds ".onion", ".test", ".invalid", "home.arpa", "resolver.arpa", and "service.arpa" as empty auth zones that can be overwritten by the operator.

There are no tests yet, I'll write those later but I could use feedback.

Closes: #17726

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]

Coverage Report for CI Build 32963491846

Coverage increased (+4.1%) to 71.17%

Details

• Coverage increased (+4.1%) from the base build.
• Patch coverage: 4 uncovered changes across 1 file (20 of 24 lines covered, 83.33%).
• 98 coverage regressions across 15 files.

Uncovered Changes

File	Changed	Covered	%
pdns/recursordist/reczones.cc	16	12	75.0%
Total (3 files)	24	20	83.33%

Coverage Regressions

98 previously-covered lines in 15 files lost coverage.

Top 10 Files by Coverage Loss	Lines Losing Coverage	Coverage
pdns/snmp-agent.cc	32	63.64%
pdns/dnsdistdist/dnsdist-snmp.cc	28	55.29%
pdns/recursordist/test-syncres_cc1.cc	8	80.05%
pdns/dnsdistdist/dnsdist-concurrent-connections.cc	4	90.65%
pdns/dnsdistdist/dnsdist-healthchecks.cc	3	54.55%
pdns/logging.cc	3	81.4%
pdns/recursordist/aggressive_nsec.cc	3	65.75%
pdns/recursordist/syncres.cc	3	81.39%
pdns/recursordist/test-syncres_cc2.cc	3	79.35%
pdns/tsigverifier.cc	3	77.22%

---

Coverage Stats

Relevant Lines:	173365
Covered Lines:	135299
Line Coverage:	78.04%
Relevant Branches:	82900
Covered Branches:	47084
Branch Coverage:	56.8%
Branches in Coverage %:	Yes
Coverage Strength:	6710744.98 hits per line

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💛 - Coveralls

[omoerbeek]

In the docs you suggest some domain can be overridden or forwarded and others not, but I don't see how that is achieved, all domains seem to be handled in a similar way (if then new flag is set to true).

[pieterlexis]

In the docs you suggest some domain can be overridden or forwarded and others not, but I don't see how that is achieved, all domains seem to be handled in a similar way (if then new flag is set to true).

This is true, I'll see how I can rephrase this.