lib/modules: move modules out of lib

lib/evalService.nix

@@ -0,0 +1,29 @@
+/*
+  Example usage:
+
+  ```nix
+  evalService = import /this/file.nix { inherit lib clanLib; };
+  result = evalService { modules = []; prefix = []; };
+
+  => result.config
+  => result.options
+  ```
+*/
+{ lib, clanLib }:
+# <lambda evalService>
+{ modules, prefix }:
+lib.evalModules {
+  class = "clan.service";
+  specialArgs._ctx = prefix;
+  modules = [
+    # Base module
+    ./service-module.nix
+    # Feature modules
+    (lib.modules.importApply ./api-feature.nix {
+      inherit clanLib prefix;
+    })
+  ]
+  ++
+    # Modules of caller
+    modules;
+}