convert: construct ziggy AST rather than bytes?

[LewisGaul]

When converting to ziggy format (JSON->Ziggy being the one mapping currently implemented), would it make more sense to construct a ziggy.Ast object rather than directly writing Ziggy snippets as bytes (via std.ArrayList(u8).writer())?

The main advantage I can see for writing directly is that the writer for the final destination (file/stdout) could be passed through giving streaming output as conversion is performed and reducing memory usage. However, this is not currently done, the writer is simply associated with an ArrayList(u8).

Pros:

• Less error prone(?)
• Get proper formatting by simply printing the AST

Cons:

• Memory impact?

I'd be happy to have a go at this change if there's interest.