Add zig implementation

[SphericalKat]

Background: I was quite happy to see a zig implementation being PRed in #16, but I quickly ran into hiccups when using it.

1. It only supports HUML v0.1.0. I wanted support for the latest and greatest v0.2.0.
2. It does not support serializing into HUML. Deal breaker.
3. It does not support de/serializing from/to Zig structs. This results in a clunky API where I have to manually do a lot of grunt work which should be abstracted away by a library.

Compare this

const result = huml.parse(input, allocator);
switch (result) {
    .document => |doc| {
        var document = doc.doc;
        defer document.deinit();

        const db = document.root.get("database").?;
        const host = db.get("host").?.asString().?;
        const port = db.get("port").?.asInt().?;
        
        const options = db.get("options").?;
        const pool_size = options.get("pool_size").?.asInt().?;
    },
    // ...
}

To my implementation

const huml = @import("humlz");
const std = @import("std");

const Config = struct {
    host: []const u8,
    port: u16,
    debug: bool = false,
};

const data =
    \\host: "localhost"
    \\port: 8080
    \\debug: true
;

var parsed = try huml.parseInto(Config, allocator, data);
defer parsed.deinit();

std.debug.print("Connecting to {s}:{d}\n", .{parsed.value.host, parsed.value.port});

Feels a lot cleaner imo! Especially type safe error handling.

[lurch]

Does 6089bac mean that this is no longer needed?