Add a button to upload a JSON file with the interview structure

[nonprofittechy]

It should include:

1. A representation of the questions of the interview, including question, subquestion, fields, and datatypes. It will only include non-built-in questions.
2. An interview order block that includes both built-in and custom fields, just the top one per each screen

Sample PDF:
Fax_cover_sheet.pdf

Sample JSON formats, showing some acceptable variations in the input: it can be a dictionary with a key "questions", one with both "questions" and "interview order", or just a list of questions without an outer dictionary.

fax_cover_sheet.json
fax_cover_sheet_from_chatgpt.json
fax_cover_sheet_no_interview_order.json

[nonprofittechy]

See also #907