In preparation of our migration to the new Nimble-based setup
and [nim-workspace][1], we switch to a new model where the vendor
packages are no longer imported through a locally generated Nimble
dir, but rather through an auto-generated `nimbus-build-system.paths`
file that features regular `--path:` statements.
This file will be imported only within the nimbus-build-system
environment in order to avoid any unwanted interference in working
copies based on the new Nimble setup.
[1]: https://github.com/status-im/nim-workspace
4b83208a19