Add support for Cloudflare Web Analytics

[MiguelClaramunt]

Have you checked that your feature request isn't already filed?

• I read through FAQ and searched through the past issues, none of which addressed my feature request.
• Yes, I have checked that this feature request isn't already filed.

Description & Motivation

Similarly to Google Analytics, add support for Cloudflare Web Analytics

Pitch

When setting up

# _config.yml
enable_google_analytics: false
cloudflare_analytics: <CF-WEB-ANALYTICS-TOKEN>

the Cloudflare Analytics tracking script will be inserted to the webpage.

Alternatives

No response

Additional context

No response