convert-app-forms - calculations are evaluated regardless of their relevance

[kennsippell]

Enketo evaluates calculation fields regardless of their relevance condition.
https://community.kobotoolbox.org/t/calculate-in-dynamic-repeat-activated-despite-skip-giving-error-for-online-submission-edit/15565/28

This is confusing and not intuitive and reults in some confusing investigations like medic/cht-conf-test-harness#133. In general, errors appear as JavaScript console errors like Evaluation failed: FormLogicError.

The developer experience would be improved if we brought these errors earlier. It would be an improvement if cht-conf errored (or warned?) when calculate fields have a relevance condition. This can always be implemented as if(relevance_condition, calculate_logic, '')