[npm] hover should show relevant latest version

In a `package.json`, when you hover the version for a dependency it will show the "[Latest version](https://github.com/Microsoft/vscode/blob/9a03a86c0a54a24c355bd950ddad91a0e74de6dd/extensions/npm/src/features/packageJSONContribution.ts#L303)". I think it would be useful to (also) show the _relevant_ latest version, which might differ if using a version prefix like `^` or `~`.