Bugfix: disaggregating map results by nested groups questions

[magicznyleszek]

Description

The problem was because FE code ignored nested groups. I introduced a nice function that generates a list of survey questions with a flat path of each one (could be useful in other places). Added a test for it too.

Related issues

Fixes #1476

[jnm]

Hey @magicznyleszek, this looks good. One question I have is about QUESTION_TYPES. This is not used by the Coffee code, so I'm guessing it needs to be kept manually in sync with another list. Is this preparation for future work?

[magicznyleszek]

@jnm in the coffee code unfortunately there is not a single list with configs for question types. If you're referring to jsapp/xlform/src/view.icons.coffee - I can use es6 files there easily (i.e. constants = require '../../js/constants'). I can also build the other config-like places in coffee code using the constant :> Answering your question - I try to not touch the coffee code if I don't need to, as I assume hope it will some day go away 🤞

[magicznyleszek]

@jnm ok I tried it and it was easy and nice - see 8418952 :)