Add openarc-genkey so that we don't have to rely on opendkim

[lquidfire]

Currently, OpenARC relies on opendkim-genkey to be installed in order to generate keys (this is the method mentioned). The keys can also be generated manually by using openssl.

This now merges openarc's own openarc-genkey (a modified version from opendkim) into openarc, so as to no longer rely on opendkim-genkey being installed.

[flowerysong]

Please create PRs against main, not devel; devel is a highly fluid branch with frequent rebases and force pushes, and mainly exists to check that CI passes for things I don't want to open a PR for. It does not provide a stable base to develop on top of, and there's never a reason for a PR to target it.

I have mixed feelings about this overall, which would be less mixed if this tool weren't written in Perl. If we have to introduce another run-time dependency for the package I would much prefer that it be Python, since that's already a (weak) compile-time dependency. I'm on vacation this week so I shouldn't really be spending time on work stuff, but this is a fairly trivial script so I might take a swing at rewriting it after that.

[flowerysong]

Or maybe I'll start on it now. https://github.com/flowerysong/OpenARC/blob/eba0daa97bf32ccae0d0130955ace423d5145bdc/contrib/openarc-keygen is gratuitously incompatible in fun little ways, but it appears to more or less work.

[lquidfire]

Looks good to me. Some different flags for command line options, but I think pretty much everything is there. Output looks good to me, too. Thanks for setting that up; I would have only had time again towards the weekend.

I agree with not adding more dependencies.

Enjoy your vacation!