Proposal: let's use `rfr`

[rfr](https://github.com/warmsea/node-rfr) allows to make all requires from the root of the project, reducing the cognitive load by avoiding to have in mind where is a file to realize where a required module lives.

From it's README page:
> allows you to require modules in your project with `rfr('lib/module1.js')` instead of something like require `('../../lib/module1.js')`

I offer myself to make such a change should be the idea accepted.

Read the linked rfr README first to understand its root-based require behavior. Then review the repository's current require usage and determine the scope of applying the proposal consistently; the work is done when the adoption decision and resulting require changes are complete and the existing test suite still passes.

Written by the indexing model from the issue text.