ctex fontset founderfree: Only use total free founder fonts in ctex

ctex-fontset-founderfree.def

\ProvidesExplFile{ctex-fontset-founderfree.def}
{\ExplFileDate}{2.5.5}{\ExplFileDescription}
\ctex_fontset_case:nnn
{
  % TODO: Set font for pdfTeX
}
{
  % TODO: Set font for upTeX
}
{
  % Set font for XeTeX
  \setCJKmainfont { FZShuSong-Z01 }
  [ BoldFont = FZHei-B01, ItalicFont = FZKai-Z03 ]
  \setCJKsansfont { FZHei-B01 }
  \setCJKmonofont { FZFangSong-Z02 }
  \setCJKfamilyfont { zhsong } { FZShuSong-Z01  }
  \setCJKfamilyfont { zhhei  } { FZHei-B01      }
  \setCJKfamilyfont { zhkai  } { FZKai-Z03      }
  \setCJKfamilyfont { zhfs   } { FZFangSong-Z02 }
}
\NewDocumentCommand \songti   { } { \CJKfamily { zhsong  } }
\NewDocumentCommand \heiti    { } { \CJKfamily { zhhei   } }
\NewDocumentCommand \fangsong { } { \CJKfamily { zhfs    } }
\NewDocumentCommand \kaishu   { } { \CJKfamily { zhkai   } }