Integrate fstformat.jl

[phillc73]

https://github.com/xiaodaigh/fstformat.jl

Ultimately, I'd like to use Query.jl syntax on FST files. I think integrating them here needs to be the first step?

[davidanthoff]

I took a first stab at a full integration into the stack: https://github.com/davidanthoff/FstFiles.jl.

I think the missing piece is really just that xiaodaigh/FstFileFormat.jl#1 gets resolved.