Check for events/RSVPs created by user before trying to disapprove a user

[punchagan]

A user can be disapproved using a link.. and multiple admins get the emails to approve or disapprove. If an admin reacts late, and tries to disapprove a user who has already created some data on the app, it can lead to problems. The best way would be to prevent such a user from being disapproved.

The CLI provides ways to delete/merge users, if requried.

[punchagan]

canonicalize_users only checks for RSVPs and could still cause issues if the user has created events or posts. There needs to be a way to dynamically check for all references and replace them.