Improve npm workspace processing

[AyanSinhaMahapatra]

• Handle cases where the workspace root package.json has a name
• Yield correctly dependencies from workspaces
• Properly populate for_package fields for workspaces
• Fix a pnpm-lock.yaml parsing bug where we were failing/adding namespaces wrongly

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)

[JonoYang]

@AyanSinhaMahapatra Looks good!

[AyanSinhaMahapatra]

Thanks @JonoYang , merging!