feat(cbor/unstable): Introduce @std/cbor

[BlackAsLight]

Closes #5479

This pull request introduces a CBOR implementation based off the RFC 8949 spec from scratch. At the moment it only introduces encodeCbor/decodeCbor functions (which operate in a sync manner and therefore is limited to JavaScript's limitations on memory usage around variable sizes) and Byte, Text, Array, Map, and Sequence Encoder Streams for larger amounts of data or if wanting to work with indefinite length types. The decoding stream methods are yet to be committed to this pull request.

Example

import { assert, assertEquals } from "@std/assert";
import { decodeCbor, encodeCbor } from "@std/cbor";

const rawMessage = [
  "Hello World",
  35,
  0.5,
  false,
  -1,
  null,
  Uint8Array.from([0, 1, 2, 3]),
];

const encodedMessage = encodeCbor(rawMessage);
const decodedMessage = decodeCbor(encodedMessage);

assert(decodedMessage instanceof Array);
assertEquals(decodedMessage, rawMessage);

[codecov]

Codecov Report

Attention: Patch coverage is 67.44604% with 362 lines in your changes missing coverage. Please review.

Project coverage is 95.49%. Comparing base (6a4eb6c) to head (60ca9ae).

Files with missing lines	Patch %	Lines
cbor/decode_stream.ts	36.07%	217 Missing and 1 partial ⚠️
cbor/encode_stream.ts	62.87%	111 Missing ⚠️
cbor/encode.ts	89.17%	17 Missing ⚠️
cbor/decode.ts	95.08%	12 Missing ⚠️
cbor/_common.ts	93.75%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5909      +/-   ##
==========================================
- Coverage   96.28%   95.49%   -0.80%     
==========================================
  Files         496      502       +6     
  Lines       39605    40717    +1112     
  Branches     5841     6027     +186     
==========================================
+ Hits        38134    38881     +747     
- Misses       1429     1793     +364     
- Partials       42       43       +1     

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[kt3k]

I wonder if these need to be classes when they both don't have any instance states.

How about making them just deocde and encode functions? That mirrors the structure of std/msgpack

[BlackAsLight]

I wonder if these need to be classes when they both don't have any instance states.

How about making them just deocde and encode functions? That mirrors the structure of std/msgpack

Sure. I was trying to mirror the structure of TextEncoder/TextDecoder, but this other structure seems more common in the std.

[kt3k]

Side note: TextDecoder stores some chunk from the previous decode when stream option is specified. Probably that is why it's implemented as a class

[iuioiua]

@BlackAsLight, could you please draft this PR and un-draft once ready for us to review?