Add a test with unquoted zero and double encoedd utf-8

  - test file was found in the wild: GOCCY/Compiler-Lexer-0.18.tar.gz built
    with LEONT/Module-Build-0.4205.tar.gz produced it as MYMETA.json
  - perl 5.8.5 trips over it, many other perls can parse it
  - open question is how they deal with the double encoded utf-8