Track the number of semicolons in multidimensional expressions

[domluna]

ref domluna/JuliaFormatter.jl#532

The current way this is being done in JuliaFormatter is kind of hacky and could be greatly simplified if this is stored in the meta or trivia fields. Is this a viable approach?

[pfitzseb]

Semicolons aren't explicitly tracked on master, but ncat/nrow expressions now include their dimensionality. That should almost always be enough info, except for

[1 2;;
 3 4]

I think. It's of course always valid to rewrite that to [1 2 3 4], so I'm not sure if you strictly need that info.