Add HLSL language support

[kb10uy]

• This PR adds support for HLSL.
• The embedded lexer is converted from Pygments using Forest0923's script (Add pygments2chroma_xml.py #664).
• HLSL support was added in Pygments 2.3, but it's not imported into Chroma yet.

I need it for describe shader codes in my blog. :)

[alecthomas]

Thanks!