fix: only eval enable option if visible

When using `lib.mkRenamedOptionModule`, the trace warning is emitted
whenever the option is accessed.

Because we iterate and check the .enable option of all the programs, the
renamed option gets accessed all the time.

So we check if the option is "visible" before checking in, which
`lib.mkRenamedOptionModule` sets to false.

Fixes #211

Author: zimbatm

Diff for: module-options.nix

@@ -1,4 +1,5 @@
 { config
+, options
 , lib
 , pkgs
 , ...
@@ -197,11 +198,14 @@ in
           package used to do the formatting.
         '';
         defaultText = lib.literalMD "Programs used in configuration";
-        default = pkgs.lib.concatMapAttrs
-          (
-            k: v: if v.enable then { "${k}" = v.package; } else { }
-          )
-          config.programs;
+        default =
+          pkgs.lib.concatMapAttrs
+            (
+              k: v:
+                if options.programs.${k}.enable.visible && v.enable then
+                  { "${k}" = v.package; } else { }
+            )
+            config.programs;
       };
       check = mkOption {
         description = ''