[WIP] Migrate code into a proper Nix module and use said module

modules/genebean/default.nix

@@ -0,0 +1,5 @@
+{ ... }: {
+  imports = [
+    #
+  ]
+}

modules/genebean/sample.nix

@@ -0,0 +1,26 @@
+{ config, lib, pkgs, ... }:
+with lib;
+let
+  cfg = config.genebean.sample;
+in {
+  imports = [
+    # paths of other modules
+  ];
+
+  options.genebean.sample = {
+    enable = mkEnableOption "Enable the genebean sample module";
+
+    foo = mkOption {
+      type = types.str;
+      default = "defaultFoo";
+      description = "An example string option for the genebean sample module.";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    # configuration settings when enabled
+    genebean.sample = {
+      # option definitions
+    };
+  };
+}