add `delete_protection` to the Cluster resource and data source

[rgcase]

Enabling delete protection on a cluster causes attempts to delete the cluster to fail. Users can set this to protect against accidental deletion of important clusters by making deletion a two-step process. To delete a protected cluster, first disable delete protection.

Commit checklist

• [x] Changelog
• [x] Doc gen (make generate)
• [x] Integration test(s)
• [x] Acceptance test(s)
• [x] Example(s)

[rgcase]

Thanks for all the help getting this merged!