feat: preserve yaml anchors and aliases w/ single string value when updating pnpm-workspace.yaml

[younggglcy]

Description

1. PackageMeta, originally as an interface, is turned into a union type, and GlobalPackageMeta is exported
2. since raw cannot provide more precise information, yaml's Document model is used to find anchors and aliases, thus js-yaml is dropped.

Linked Issues

fix #150

Additional context

[sxzz]

Consider the use case below

defines:
  - &react ^18.2.0

catalog:
  react: *react
  react-dom: *react

It's not working in this PR.

[younggglcy]

Consider the use case below

defines:
  - &react ^18.2.0

catalog:
  react: *react
  react-dom: *react

It's not working in this PR.

Thanks for the rapid reply❤️, but the test parts are not finished yet. Currently, the tests cannot
be passed locally, so there may be something wrong with mocking, I'll take my spare time to fix it.

And I'm wondering if we should support this use case, though this use case make sense, but it's not a valid yaml-schema for pnpm-workspace.yaml

[sxzz]

pnpm doesn't prohibit adding unknown fields. I'm not sure if this is a good use case, but my repository currently uses it this way.