open questions: add 'allowEmpty' flag

[noamoss]

some of the questions (not all of them) should enable the user to submit without typing in ('anonymous' for the name is the clearest examples, but we already have two other cases in which currently we have to ask a yes/no question just to confirm in advance the user has some info to type in:

• האם את/ה יודעים את שם חברת האבטחה?
• האם את/ה יודעים את שם המאבטח/ת?

we should minimize/subtract these steps, without giving up on the standard content validation assumption for most of the question

notice

this issue is relevant for the reportit-agent part as well.

alternative solution:

handle the split method when an empty string is submitted into a this.content.setTextArea():