Endpoint to send another verification email

https://redmine.teklia.com/issues/7318

Requires #1759 (closed)

Please create a new SendVerificationEmail endpoint, a CreateAPIView at the /api/v1/user/verify-email/send/ URL. This endpoint requires authentication as any user, not just a verified user.

It does not take any request body at all, meaning that calling it with the API client as client.request('SendVerificationEmail') with no arguments at all should be possible.

When the user is already verified, it returns an HTTP 400 stating so.

When the user is not verified, it calls arkindex.project.triggers.send_verification_email to send a new verification email to the currently authenticated user, then returns an HTTP 202 status code.