writers.makeDataWriter: Deprecate

pkgs/build-support/writers/data.nix

···
   #   writeJSON = makeDataWriter { input = builtins.toJSON; output = "cp $inputPath $out"; };
   #   myConfig = writeJSON "config.json" { hello = "world"; }
   #
-  makeDataWriter = { input ? lib.id, output ? "cp $inputPath $out" }: nameOrPath: data:
+  makeDataWriter = lib.warn "pkgs.writers.makeDataWriter is deprecated. Use pkgs.writeTextFile." ({ input ? lib.id, output ? "cp $inputPath $out" }: nameOrPath: data:
     assert lib.or (types.path.check nameOrPath) (builtins.match "([0-9A-Za-z._])[0-9A-Za-z._-]*" nameOrPath != null);
     let
       name = last (builtins.split "/" nameOrPath);