Add `captcha/verify-token` profile with `mock` and `cloudflare-turnstile` maps

[janhalama]

Description

This PR adds captcha/verify-token profile with mock and cloudflare-turnstile maps.

Motivation and Context

captcha/verify-token profile is referenced in a new blog post comparing CAPTCHA providers. To keep the PR small, only the Cloudflare Turnstile provider map is included. Google reCAPTCHA and hCaptcha providers will come later in separate PRs.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] I have read the CONTRIBUTING document.
• [x] I haven't repeated the code. (DRY)
• [x] I have added tests to cover my changes.
• [ ] All new and existing tests passed.