[Org Application/Onboarding] Move transparency mode prompt from application to onboarding

At the moment, when orgs apply at https://hcb.hackclub.com/hcb/apply we ask whether they'd like transparency mode on. We should move that prompt to when onboard onto HCB.

This likely means we'll need to create an onboarding state for orgs. When in onboarding, there will be questions/fields they will fill out; including whether they'd like transparency mode on.