feat: YAML parser

[magne4000]

New loadYaml util to parse existing YAML documents. This function uses yaml, and returns a Document.

Usage example

import { loadYaml, type TransformerProps } from "@batijs/core";

export default async function getYaml(props: TransformerProps) {
  const document = await loadYaml(props);

  // Add a node to the document
  document.add(document.createNode({ something: true }));

  // You can return the document directly
  return document;
  // Or if you want to customize `toString` options
  return document.toString({ ... });
}