Fix parentfolder check

[maerten]

This fixes a small issue where imports are incorrectly rewritten.

The bug

Example:

// in file: cypress/integration/test.ts
import config from '../../src/config'

was being rewritten to

# in file: cypress/integration/test.ts
import config from 'config'

Fix

This PR extends isParentFolder to check if the import can be safely rewritten.