[Backend] Set Firebase user email verification status

[dpang314]

Description

• When a user is created their email is not verified.
• This is reflected in MongoDB, but not hasn't been implemented with Firebase, which we use for authentication.

Acceptance Criteria

• In /api/user/user POST when a user is created update associated Firebase user to have emailVerified: false
• in /api/auth/verify PATCH on a successful verification, update the Firebase user to have emailVerified: true
• in firebase_storage_rules.txt restrict both read and write to require request.auth.emailVerified to be true

Other Notes

• https://firebase.google.com/docs/auth/admin/manage-users#update_a_user
• https://firebase.google.com/docs/rules/rules-and-auth
• https://firebase.google.com/docs/rules/rules-language#storage

[thanasis457]

In Firebase, emailVerified: false is the default configuration if verified status is not provided. Either way I added some code to ensure that is is set to false for new users.