feat(yaml/unstable): allow to add custom types for parse and stringify

[oscarotero]

This change introduce a new option to add custom types for parse and stringify functions of YAML, which can fix #5680.

For example:

import { parse, type ImplicitType } from "@std/yaml";

const smile: ImplicitType = {
  tag: "tag:custom:smile",
  resolve: (data): boolean => data === "=)",
  construct: (): string => "🙂",
  predicate: (data): data is string => data === "🙂",
  kind: "scalar",
  represent: (): string => "=)",
};

const yaml = `
title: =)
tags:
  - =)
  - bar
`

const result = parse(yaml, { extraTypes: [ smile ] }
console.assert(result.title === "🙂");

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

❌ Patch coverage is 70.00000% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.11%. Comparing base (b58b295) to head (73da044).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
yaml/unstable_parse.ts	58.33%	15 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6841      +/-   ##
==========================================
- Coverage   94.18%   94.11%   -0.07%     
==========================================
  Files         575      578       +3     
  Lines       42446    42604     +158     
  Branches     6742     6775      +33     
==========================================
+ Hits        39977    40098     +121     
- Misses       2419     2455      +36     
- Partials       50       51       +1     

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[kt3k]

We have policy of accepting new feature as unstable first https://github.com/denoland/std/blob/main/.github/CONTRIBUTING.md#new-features-in-stable-packages-version--100

Can you copy parse.ts to unstable_parse.ts and make these changes to there? (Also map ./unstable-parse to ./unstable_parse.ts, that enables users to import it via jsr:@std/yaml/unstable-parse

[oscarotero]

@kt3k I moved everything to the unstable files (the unstable_stringify.ts already existed so I just had to create unstable_parse.ts) and all lint issues caused by private types are fixed. The only thing Ieft is the PR title, but I have no idea how to fix it.

[kt3k]

LGTM

[kt3k]

Thank you for documenting this!

[devingfx]

Why create a whole copy of each modules just to re-export stuff? instead of just make the module _schema.ts public...

Let people access this schema module and they can even hack the original schemas... (Just needs a "At your own risk" notice).

I feel this PR a bit overkill for initial goal ...