Reference: #13005
Reference: #13006

Changes:

```
FEATURES:

* **New Resource:** `aws_guardduty_organization_admin_account`
* **New Resource:** `aws_guardduty_organization_configuration`
```

Output from acceptance testing:

```
--- PASS: TestAccAWSGuardDuty (137.70s)
    --- PASS: TestAccAWSGuardDuty/Detector (58.97s)
        --- PASS: TestAccAWSGuardDuty/Detector/basic (41.45s)
        --- PASS: TestAccAWSGuardDuty/Detector/import (17.52s)
    --- PASS: TestAccAWSGuardDuty/OrganizationAdminAccount (31.74s)
        --- PASS: TestAccAWSGuardDuty/OrganizationAdminAccount/basic (31.74s)
    --- PASS: TestAccAWSGuardDuty/OrganizationConfiguration (46.99s)
        --- PASS: TestAccAWSGuardDuty/OrganizationConfiguration/basic (46.99s)
```

…comments

Reference: #13034 (review)

Output from acceptance testing:

```
    --- PASS: TestAccAWSGuardDuty/OrganizationAdminAccount (44.91s)
        --- PASS: TestAccAWSGuardDuty/OrganizationAdminAccount/basic (44.91s)
```