Reimplement (named) constituent jobs (+globbing) based on nix-eval-jobs

Depends on https://github.com/nix-community/nix-eval-jobs/pull/349 & #1421.

Almost equivalent to #1425, but with a small change: when having e.g. an
aggregate job with a glob that matches nothing, the jobset evaluation is
failed now. This was the intended behavior before (hydra-eval-jobset
fails hard if an aggregate is broken), the code-path was never reached
however since the aggregate was never marked as broken in this case
before.

t/jobs/config.nix

@@ -0,0 +1,14 @@
+rec {
+  path = "/nix/store/l9mg93sgx50y88p5rr6x1vib6j1rjsds-coreutils-9.1/bin";
+
+  mkDerivation = args:
+    derivation ({
+      system = builtins.currentSystem;
+      PATH = path;
+    } // args);
+  mkContentAddressedDerivation = args: mkDerivation ({
+    __contentAddressed = true;
+    outputHashMode = "recursive";
+    outputHashAlgo = "sha256";
+  } // args);
+}