Changes to allow programmatic use of rdl-data via python package

[ConnectedSystems]

These changes are principally for the in-development RDL interface over here

The set of changes allows rdl-data to be installed locally as its own package, which negates the need to modify system paths.

Changes may break current workflow, so please consider this a draft PR until everything is confirmed to be working or that this can replace the current workflow.

$ cd rdl-data
$ pip install -e .

This allows its use from an external interface without having to modify system paths:

import challenge_fund_db as cf

print(cf.hazard)