Support custom CSRF_COOKIE_NAME in front-end

[jochenklar]

Right now csrftoken is hardcoded (https://github.com/rdmorganiser/rdmo/blob/main/rdmo/core/static/core/js/core.js#L6), in the new front-end this should be taken from settings.CSRF_COOKIE_NAME and settings.CSRF_HEADER_NAME.