Support and respect export conditions for lookupNodeModuleSubpath

[pi0]

Following up fix in #210, we should support conditions option for lookupNodeModuleSubpath in order to allow filtering based on them. currently the first export from flatted exports will be used to guess which might be inaccurate.

[danielroe]

Here's an example reproduction: https://stackblitz.com/edit/stackblitz-starters-w3d5xq?file=index.js

[babs20]

Hello, @pi0!

I would love to contribute a PR to resolve this issue. Could you clarify what we are expecting to pass to the conditions option and what the expected behavior would be in lookupNodeModuleSubpath?

[pi0]

@babs20 this page might explain it. Essentially when traversing the exports object, we match the first condition (from conditions array user pass) and then fallback to default if it exists. LMK if wasn't clear or just feel free to draft some progress would be happy to review.