dnsdist: Disable Lua configuration directives in YAML mode

[rgacogne]

Short description

This commit restricts the Lua directives available to a Lua script loaded alongside with a YAML configuration, disabling all Lua configuration directives. This prevents a mess when settings are set to different values in YAML and Lua, and make it clear that the when a YAML configuration is used, any Lua file should only be used to provide functions to the YAML configuration.
This behaviour can be reverted via the enableLuaConfiguration directive if really needed.

Checklist

I have:

• read the CONTRIBUTING.md document
• 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)

[miodvallat]

Not pretending to understand all of this, but no alarm signals raised while reading.

[coveralls]

Pull Request Test Coverage Report for Build 13326662864

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 27 of 33 (81.82%) changed or added relevant lines in 2 files are covered.
• 6269 unchanged lines in 77 files lost coverage.
• Overall coverage increased (+0.03%) to 64.632%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pdns/dnsdistdist/dnsdist.cc	7	9	77.78%
pdns/dnsdistdist/dnsdist-lua.cc	20	24	83.33%

Files with Coverage Reduction	New Missed Lines	%
ext/lmdb-safe/lmdb-typed.hh	1	73.19%
modules/gpgsqlbackend/gpgsqlbackend.cc	1	88.62%
pdns/pollmplexer.cc	1	83.66%
pdns/recursordist/rec-rust-lib/rust/src/bridge.hh	1	0.0%
pdns/recursordist/sortlist.hh	1	75.0%
ext/probds/murmur3.cc	2	94.12%
pdns/dnsname.hh	2	91.4%
pdns/dnstap.cc	2	70.97%
pdns/recursordist/secpoll-recursor.cc	2	50.0%
pdns/tcpiohandler.cc	2	68.18%

Totals
Change from base Build 13326341755:	0.03%
Covered Lines:	127921
Relevant Lines:	166884

---

💛 - Coveralls