Add YAML std module

[lsagetlethias]

Setup YAML module as it was made in denoland/std#528.

This a a port from nodeca/js-yaml.

Typing internally is quite messy but the endpoints themselves (parse and stringify) are ready to use.

deno fmt is ok
deno test is ok

Additional tests from original repo's old issues are not usable as they mainly use third party library not yet ported in deno.
Like in this test: https://github.com/nodeca/js-yaml/blob/665aadda42349dcae869f12040d9b10ef18d12da/test/25-dumper-fuzzy.js#L4 where the fast-check lib is used.

[CLAassistant]

All committers have signed the CLA.

[ry]

LGTM

It's a lot of code, but I guess YAML is just a wildly complicated specification.

It's nice you've ported this all to TypeScript! Thanks - this is great to have!

[tunnckoCore]

Any thoughts/reasons why js-yaml instead of https://www.npmjs.com/package/yaml? I'm still not sure myself which one to use when I need it, but at least the API is more sane .parse and .stringify.

[lsagetlethias]

Well ; in term of date of creation, number of stars, stability, and number of download per weeks, js-yaml is way before any other yaml lib https://www.npmtrends.com/js-yaml-vs-yaml

[tunnckoCore]

Yea, I know, was just wondering.

Okay, then wouldn't it better to expose different (and I think more intuitive) API and don't inherit it from js-yaml, since Deno is still in early stages.

[lsagetlethias]

That's what I've done:

deno/std/encoding/yaml.ts

Line 6 in 2cd22b5

export * from "./yaml/parse.ts";

Both endpoint types are available. Including classical parse / stringify standard combo ☺️