Incompatible with yarn2 and PnP

[ertrzyiks]

The root property is calculated assuming the folder structure with node_modules https://github.com/oclif/config/blob/71fb6d9b98bff6c2ccee6961c8afa8403a8b1366/src/plugin.ts#L109

a project attempting to use Yarn Plug'n'Play fails to load with

could not find package.json with