Support alternative Cloudflare API token file format

[naanlizard]

Small issue here, other services (letsencrypt and stuff using it) tend to use cloudflare's API key in the form of

# Cloudflare API token used by Certbot
dns_cloudflare_api_token = 0123456789abcdef0123456789abcdef01234567

https://certbot-dns-cloudflare.readthedocs.io/en/stable/

would it be possible to add support for that formatting so I don't need as many files kicking around?

Originally posted by @naanlizard in #668 (comment)

[favonia]

@naanlizard Thank you. I will have to think about this due to the additional complexity, and this feature might have lower priority on my list (sorry). On the other hand, I wonder if your true concern is the burden to maintain consistency across multiple configuration files, which I deeply sympathize! If so, I think tools like conf might help.