lib/tests/modules: Test non-strictness some more

Doesn't seem to have been a problem actually, but now it won't
regress.

lib/tests/modules/declare-attrsOf.nix

···
-{ lib, ... }: {
+{ lib, ... }:
+let
+  deathtrapArgs = lib.mapAttrs
+    (k: _: throw "The module system is too strict, accessing an unused option's ${k} mkOption-attribute.")
+    (lib.functionArgs lib.mkOption);
+in
+{
   options.value = lib.mkOption {
     type = lib.types.attrsOf lib.types.str;
     default = {};
   };
+  options.testing-laziness-so-don't-read-me = lib.mkOption deathtrapArgs;
 }

lib/tests/modules/freeform-nested.nix

···
-{ lib, ... }: {
+{ lib, ... }:
+let
+  deathtrapArgs = lib.mapAttrs
+    (k: _: throw "The module system is too strict, accessing an unused option's ${k} mkOption-attribute.")
+    (lib.functionArgs lib.mkOption);
+in
+{
   options.nest.foo = lib.mkOption {
     type = lib.types.bool;
     default = false;
   };
+  options.nest.unused = lib.mkOption deathtrapArgs;
   config.nest.bar = "bar";
 }