Add configurable stream-tools option

lib/default.nix

@@ -0,0 +1,32 @@
+{lib, ...}: let
+  inherit (lib) mkOption strings;
+  inherit (lib.attrsets) filterAttrs mapAttrsToList;
+  inherit (lib.types) bool;
+in rec {
+  disabled = {enable = false;};
+  enabled = {enable = true;};
+  ifThenElse = cond: t: f:
+    if cond
+    then t
+    else f;
+  mkOpt = type: default: description:
+    mkOption {inherit type default description;};
+  mkOpt' = type: default: mkOpt type default null;
+  mkBoolOpt = mkOpt bool;
+  mkBoolOpt' = mkOpt' bool;
+  mkPxeMenu = args:
+    ''
+      UI menu.c32
+      TIMEOUT 300
+    ''
+    + strings.concatStringsSep "\n" (mapAttrsToList
+      (
+        name: value: ''
+          LABEL ${name}
+            MENU LABEL ${value.content.label}
+            KERNEL ${value.content.kernel}
+            append ${value.content.append}
+        ''
+      )
+      (filterAttrs (_: v: v.condition) args));
+}