The CSRF header name needs to be configurable

[vegaed]

We use a different header name than X-CSRFToken and causes testing via swagger-ui to fail against our api.

Either use the django setting or provide a way to override.

Code in question is https://github.com/vitalik/django-ninja/blob/c6d44b62a180fcf8ddfd73d67e0274a77b9d30ae/ninja/templates/ninja/swagger_cdn.html#L28