Removing Lifelines-specific pairing rules from the codebase

[hcadavid]

The design and development of this tool were guided by the implementation of pairing rules for Lifelines variables. Now that the tools and FHIR templates are decoupled from any concrete pairing-rule module, the 'core' of the tool, and the pairing rules for Lifelines should become independent projects. This requires:

1. Use an external configuration file defining which Templates will be used during the transformation, and which pairing rules will be linked to them.
2. Turn the 'core' of the tool into a self-contained NPM package, adding building and publishing tasks on GitHub actions.
3. Create a project for each dataset, each one referring to the aforementioned package, and limited to the implementation of the corresponding pairing rules and their corresponding unit tests.