Make ecobenefits aggregator usable by other modules
Make ecobenefits aggregator usable by other modules

Note: This diff looks messy, but it's really just moving `TreeBenefitsCalculator._compute_currency_and_transform_units` to be a top-level function.

clever-crow-consulting/otm-core,RickMohr/otm-core,recklessromeo/otm-core,clever-crow-consulting/otm-core,maurizi/otm-core,maurizi/otm-core,RickMohr/otm-core,recklessromeo/otm-core,recklessromeo/otm-core,recklessromeo/otm-core,clever-crow-consulting/otm-core,RickMohr/otm-core,maurizi/otm-core,clever-crow-consulting/otm-core,RickMohr/otm-core,maurizi/otm-core