Linux/Darwin thrashing

[ggPeti]

Currently, this plugin is unsuitable for multi-platform development, because the contents of the Yarn cache will be different on different platforms. Part of this is related to conditionals (https://github.com/stephank/yarn-plugin-nixify/issues/52) but another part is that some packages have different cache entries. Case in point:

where ./yarn/cache is a linux cache and ../.yarn/cache is a darwin cache.

This results in the generated nix file being back-and-forth overwritten with a different hash by team members on different platforms.

I'm not sure how to proceed from here. Maybe the plugin should accomodate for each platform separately, making it possible to configure a different output path for linux-based and darwin-based expressions.