Waiver Acceptance MUST require a guardian email

Goal:
Right now it's possible to accept a Waiver in the Parent Flow without a guardian email. This is _required_ in all systems because a copy of the accepted waiver must be emailed to the guardian on file.

UX Suggestions:
- If the email is missing and the user has just clicked Accept, Show the Name of the parent on record and request an email
- Highlight the flow step with the parent email to be entered OR display the field in the popup for immediate entry

Acceptance Criteria:
A waiver is sent after acceptance and this event, including Guardian identity and email, are recorded in a Waiver History record