image_optim: add oxipng, fix optional workers

Support for [oxipng](https://github.com/shssoichiro/oxipng) was added with [version 0.31.0](https://github.com/toy/image_optim/blob/master/CHANGELOG.markdown#v0310-2021-10-03). So we add `oxipng` as an optional dependency.

If some optional workers are disabled `image_optim` fails with an error message like:
```
Bin resolving errors:
pngout worker: `pngout` not found; please provide proper binary or disable this worker (--no-pngout argument or `:pngout => false` through options)
```
To fix the problem the flag `--no-program` is added while wrapping if the worker `program` is disabled.

pkgs/applications/graphics/image_optim/default.nix

@@ -1,9 +1,10 @@
 { lib, bundlerApp, bundlerUpdateScript, makeWrapper,
   withPngcrush ? true,       pngcrush,
-  withPngout ? true,         pngout,
+  withPngout ? false,        pngout, # disabled by default because it's unfree
   withAdvpng ? true,         advancecomp,
   withOptipng ? true,        optipng,
   withPngquant ? true,       pngquant,
+  withOxipng ? true,         oxipng,
   withJhead ? true,          jhead,
   withJpegoptim ? true,      jpegoptim,
   withJpegrecompress ? true, jpeg-archive,
@@ -15,18 +16,31 @@
 with lib;
 
 let
-  optionalDepsPath = []
-    ++ optional withPngcrush pngcrush
+  optionalDepsPath = optional withPngcrush pngcrush
     ++ optional withPngout pngout
     ++ optional withAdvpng advancecomp
     ++ optional withOptipng optipng
     ++ optional withPngquant pngquant
+    ++ optional withOxipng oxipng
     ++ optional withJhead jhead
     ++ optional withJpegoptim jpegoptim
     ++ optional withJpegrecompress jpeg-archive
     ++ optional withJpegtran libjpeg
     ++ optional withGifsicle gifsicle
     ++ optional withSvgo svgo;
+
+  disabledWorkersFlags = optional (!withPngcrush) "--no-pngcrush"
+    ++ optional (!withPngout) "--no-pngout"
+    ++ optional (!withAdvpng) "--no-advpng"
+    ++ optional (!withOptipng) "--no-optipng"
+    ++ optional (!withPngquant) "--no-pngquant"
+    ++ optional (!withOxipng) "--no-oxipng"
+    ++ optional (!withJhead) "--no-jhead"
+    ++ optional (!withJpegoptim) "--no-jpegoptim"
+    ++ optional (!withJpegrecompress) "--no-jpegrecompress"
+    ++ optional (!withJpegtran) "--no-jpegtran"
+    ++ optional (!withGifsicle) "--no-gifsicle"
+    ++ optional (!withSvgo) "--no-svgo";
 in
 
 bundlerApp {
@@ -39,16 +53,23 @@ bundlerApp {
 
   postBuild = ''
     wrapProgram $out/bin/image_optim \
-      --prefix PATH : ${lib.escapeShellArg (makeBinPath optionalDepsPath)}
+      --prefix PATH : ${lib.escapeShellArg (makeBinPath optionalDepsPath)} \
+      --add-flags "${lib.concatStringsSep " " disabledWorkersFlags}"
   '';
 
   passthru.updateScript = bundlerUpdateScript "image_optim";
 
   meta = with lib; {
-    description = "Command line tool and ruby interface to optimize (lossless compress, optionally lossy) jpeg, png, gif and svg images using external utilities (advpng, gifsicle, jhead, jpeg-recompress, jpegoptim, jpegrescan, jpegtran, optipng, pngcrush, pngout, pngquant, svgo)";
-    homepage    = "https://github.com/toy/image_optim";
-    license     = licenses.mit;
+    description = "Optimize images using multiple utilities";
+    longDescription = ''
+      Command line tool and ruby interface to optimize (lossless compress,
+      optionally lossy) jpeg, png, gif and svg images using external utilities
+      (advpng, gifsicle, jhead, jpeg-recompress, jpegoptim, jpegrescan,
+      jpegtran, optipng, oxipng, pngcrush, pngout, pngquant, svgo)
+    '';
+    homepage = "https://github.com/toy/image_optim";
+    license = licenses.mit;
     maintainers = with maintainers; [ srghma nicknovitski ];
-    platforms   = platforms.all;
+    platforms = platforms.all;
   };
 }