gtk4: move broadwayd into out

It is convenient to have it in PATH by default and does not seem to increase the output size much (+0.2M).

Just as was done to GTK 3 in https://github.com/NixOS/nixpkgs/pull/116053

pkgs/development/libraries/gtk/4.x.nix

@@ -202,6 +202,9 @@ stdenv.mkDerivation rec {
     for f in $dev/bin/gtk4-encode-symbolic-svg; do
       wrapProgram $f --prefix XDG_DATA_DIRS : "${shared-mime-info}/share"
     done
+  '' + lib.optionalString broadwaySupport ''
+    # Broadway daemon
+    moveToOutput bin/gtk4-broadwayd "$out"
   '';
 
   # Wrap demos