Add DNS settings

[Cyb3r-Jak3]

Description

Adds new Settings field to DNSRecord. Only has CNAME Flattening currently.

Has your change been tested?

Add new test and it passes

Screenshots (if appropriate):

Types of changes

What sort of change does your code introduce/modify?

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

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• This change is using publicly documented in cloudflare/api-schemas
  and relies on stable APIs.

[Cyb3r-Jak3]

Needed for cloudflare/terraform-provider-cloudflare#4595

[github-actions]

changelog detected ✅

[jacobbednarz]

cc @janik-cloudflare