Motivation for this change

Add crowbar, an afl based test framework, which some test suites in ocamlPackages depend on (index and eqaf as far as I know which have their test suites enabled in this PR).

One issue this PR currently has is that it probably doesn't make sense to run the crowbar tests on a compiler which does not support afl. We could detect afl and enable/disable the tests like this (although its not nice):

{
  doCheck = lib.hasInfix "afl" ocaml.name;
}

However, this has another issue: The affected packages have a normal test suite as well which doesn't require crowbar. Selectively activating and deactivating parts of the test suite could become rather cumbersome and I think it is not really that big of an issue since crowbar runs and compiles without any errors even when afl is not enabled.

Note that this PR also includes the eqaf update from #88467.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.