Allow users to permanently delete account from the UI

[ColinSchwarz]

Acceptance Criteria: Users must be able to permanently delete their account and all their files through the UI. This should include a warming and an "accept" button to prevent accidental deletion. Confirmation email should also be sent for users with email.

[Tbaut]

I wonder if a confirmation email is a standard thing to do.

[bkchr]

@Tbaut can I get a delete button? :see_no_evil:

[Tbaut]

Hey @bkchr, it's unlikely to happen unfortunately since this project isn't actively worked on :|