Resend confirmation email

Left over from https://github.com/UUDigitalHumanitieslab/I-analyzer-django/issues/3

For email validation, users should be able to request that the email to confirm their address is resent. Either because
- they have deleted the email
- the token for email confirmation has expired (does that happen?)

Start by locating the existing email-validation confirmation flow and how confirmation tokens are handled. Check whether tokens expire and how users currently request account-related emails. Done means users can request a new confirmation email when the original was deleted or its token has expired, with the behavior covered by the project’s existing tests.

Written by the indexing model from the issue text.