update validation records/errors for custom_hostname and certificate_pack

[nickysemenza]

resource/custom_hostname: validation tokens are now an array (`validation_records`) instead of a top level, but the only top level record that was previously here was for cname validation, txt/http/email were entirely missing.
resource/custom_hostname: also adds missing `validation_errors`, and `certificate_authority`
resource/certificate_pack: adds `validation_errors` and `validation_records` with same format as custom hostnames.

relies of lib behavior added in cloudflare/cloudflare-go#796

[github-actions]

Oops! It looks like no changelog entry is attached to this PR. Please include a release note as described in https://github.com/cloudflare/terraform-provider-cloudflare/blob/master/docs/changelog-process.md.

Example:

```release-note:TYPE
Release note
```

If you do not require a release note to be included, please add the workflow/skip-changelog-entry label.

[jacobbednarz]

@nickysemenza could you move the CHANGELOG entry to the file as the documentation mentions? that will allow it post merge to be picked up correctly.

[jacobbednarz]

acceptance tests are green

TF_ACC=1 go test $(go list ./...) -v -run "^TestAccCloudflareCustomHostname" -count 1 -parallel 1 -timeout 120m -parallel 1
?   	github.com/cloudflare/terraform-provider-cloudflare	[no test files]
=== RUN   TestAccCloudflareCustomHostnameFallbackOrigin
--- PASS: TestAccCloudflareCustomHostnameFallbackOrigin (13.94s)
=== RUN   TestAccCloudflareCustomHostnameFallbackOriginUpdate
--- PASS: TestAccCloudflareCustomHostnameFallbackOriginUpdate (23.16s)
=== RUN   TestAccCloudflareCustomHostname_Basic
=== PAUSE TestAccCloudflareCustomHostname_Basic
=== RUN   TestAccCloudflareCustomHostname_WithCustomOriginServer
=== PAUSE TestAccCloudflareCustomHostname_WithCustomOriginServer
=== RUN   TestAccCloudflareCustomHostname_WithHTTPValidation
=== PAUSE TestAccCloudflareCustomHostname_WithHTTPValidation
=== RUN   TestAccCloudflareCustomHostname_WithCustomSSLSettings
=== PAUSE TestAccCloudflareCustomHostname_WithCustomSSLSettings
=== RUN   TestAccCloudflareCustomHostname_Update
=== PAUSE TestAccCloudflareCustomHostname_Update
=== RUN   TestAccCloudflareCustomHostname_WithNoSSL
=== PAUSE TestAccCloudflareCustomHostname_WithNoSSL
=== RUN   TestAccCloudflareCustomHostname_UpdatingZoneForcesNewResource
=== PAUSE TestAccCloudflareCustomHostname_UpdatingZoneForcesNewResource
=== RUN   TestAccCloudflareCustomHostname_Import
=== PAUSE TestAccCloudflareCustomHostname_Import
=== CONT  TestAccCloudflareCustomHostname_Basic
--- PASS: TestAccCloudflareCustomHostname_Basic (10.22s)
=== CONT  TestAccCloudflareCustomHostname_Update
--- PASS: TestAccCloudflareCustomHostname_Update (21.45s)
=== CONT  TestAccCloudflareCustomHostname_Import
--- PASS: TestAccCloudflareCustomHostname_Import (14.20s)
=== CONT  TestAccCloudflareCustomHostname_UpdatingZoneForcesNewResource
--- PASS: TestAccCloudflareCustomHostname_UpdatingZoneForcesNewResource (19.54s)
=== CONT  TestAccCloudflareCustomHostname_WithNoSSL
--- PASS: TestAccCloudflareCustomHostname_WithNoSSL (10.91s)
=== CONT  TestAccCloudflareCustomHostname_WithHTTPValidation
--- PASS: TestAccCloudflareCustomHostname_WithHTTPValidation (11.00s)
=== CONT  TestAccCloudflareCustomHostname_WithCustomSSLSettings
--- PASS: TestAccCloudflareCustomHostname_WithCustomSSLSettings (10.29s)
=== CONT  TestAccCloudflareCustomHostname_WithCustomOriginServer
--- PASS: TestAccCloudflareCustomHostname_WithCustomOriginServer (10.79s)
PASS
ok  	github.com/cloudflare/terraform-provider-cloudflare/cloudflare	146.054s
?   	github.com/cloudflare/terraform-provider-cloudflare/tools/cmd/changelog-check	[no test files]
?   	github.com/cloudflare/terraform-provider-cloudflare/version	[no test files]