WordCamp teams organise standalone KidsCamps or include it in their main event. To help know WordCamp applicants plans during the vetting, add questions about KidsCamp to the WordCamp organizer application. KidsCamp lead organiser question will be visible only when a yes answer is selected in the previous question.

Also add KidsCamp information fields to the WordCamp tracker, in order to help deputies and especially Youth Events working groups work.

Fixes #275
See #720 which is similar to this

Props @sunsand187

Screenshots

How to test the changes in this Pull Request:

1. Go to WordCamp organiser application page and start filling out the form
2. Select a yes answer to the question "Are you planning to hold a KidsCamp?"
3. Submit application
4. Go to WordCamp tracker to see the application, KidsCamp should be active and information fields visible