realpath performance improvements + error handling

[SukkaW]

The PR does 2 things:

• Use fs.realpathSync.native in non-Windows environments and use fs.realpathSync on Windows
  • fs.realpathSync is 70x slower than fs.realpathSync.native: fs.realpath 70x slower than native  nodejs/node#2680
  • fs.realpathSync.native has undefined behavior with the Windows network drive, which could cause unexpected behavior.
• Caching NodeModule.realpath getter
• Make NodeModule.realpath fall back to NodeModule.path when encountering an ENOENT error.
  • When using the package.json's overwrites field with @favware/skip-dependency, the module will have a symlink point to a non-existing path, causing fs.realpathSync to choke.

[ranyitz]

Thanks @SukkaW! That looks great 👍

[ranyitz]

This is available on qnm@2.10.2 🎉