modules/test: move test derivation to an option

Introduced the `test.derivation` read-only option.

lib/default.nix

@@ -1,6 +1,5 @@
 # Args probably only needs pkgs and lib
 {
-  makeNixvimWithModule,
   pkgs,
   lib ? pkgs.lib,
   _nixvimTests ? false,
@@ -8,6 +7,6 @@
 }@args:
 {
   # Add all exported modules here
-  check = import ../tests/test-derivation.nix { inherit makeNixvimWithModule lib pkgs; };
+  check = import ../tests/test-derivation.nix { inherit lib pkgs; };
   helpers = import ./helpers.nix (args // { inherit _nixvimTests; });
 }

lib/modules.nix

@@ -23,7 +23,7 @@ rec {
       modules ? [ ],
       extraSpecialArgs ? { },
       # Set to false to disable warnings and assertions
-      # Intended for use with tests, where we may not want to check assertions
+      # Intended to aid accessing config.test.derivation
       # WARNING: This argument may be removed without notice:
       check ? true,
     }: