Use protozero for Protocol Buffer operations in dnsdist, and dnstap/outgoing for the rec

[rgacogne]

Short description

This PR:

• switches from libprotobuf to protozero to generate Protocol Buffer and dnstap messages in dnsdist ;
• same for outgoing Protocol Buffer and dnstap messages in the recursor ;
• same for dnscap2protobuf in the auth ;
• removes the dependencies on libprotobuf and proto-c ;
• removes the --with-protobuf option since protozero is always available, removing a ton of #ifdefs.

Using protozero in dnsdist results in no new allocation when a message in generated, against ~8 of them before.

Closes #9780.
Closes #9781.

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)

[rgacogne]

Great, it looks like applying our formatting script locally gives a different result than the one expected in Circle CI..

[omoerbeek]

This is a big one! I did not read everything, but in general it looks very good and I'm very happy with it.

I tested dnstap, regular protobuf and outgoing protobuf in rec (and noted one issue in the dnstap code as already mentioned).

I also reviewed the recursor changes in detail, since they are a bit tricky with adding to a partially constructed message. That all looks fine and tests ok.

Two things remain:

• It really could use more extensive regression tests.
• Also, a few symbolic constants or enums would make the code easier to read and might even have prevented the 3/4 mixup.

[rgacogne]

It really could use more extensive regression tests.

It turns out that the current regression tests are quite good, and would have caught the issue if they were run in our CI.. Which #9836 will solve. And apparently I forgot to run them locally, as I was too focused on the protobuf ones.

Also, a few symbolic constants or enums would make the code easier to read and might even have prevented the 3/4 mixup.

I'll push a couple commits doing just that in a few moments.

Thanks for the review, Otto, much appreciated!

[rgacogne]

Otto, do you want to take a look at the two latest commits before I merge this PR?

There is no rush, I won't merge it before auth-4.4.0 since I'm afraid the removal of libprotobuf might cause a few build issues here and there.

[rgacogne]

Rebased to fix a conflict introduced by the incbin removal.