adminExport: when getting fields, it is not possible to differentiate initialization from participant response

[tahini]

Here's an example log line from the csv file:

id,uuid,2024-10-17T15:42:02.814Z,,,false,false,1729179722,responses.acceptToBeContactedForHelp|responses.contactEmail|responses.homePhoneNumber

Actually, one of those responses is a response by the participant, while the others are values initialized to null when the question becomes visible. Ideally, we could differentiate 2 columns for fields with null values (initialization) and those with actual values (whether by participant or set by default by the questionnaire)