AWS::CertificateManager::Certificate - Import

1. Title

Ability to Import existing ACM certificates into CloudFormation

2. Scope of request

Ability to import an existing ACM certificate to a CloudFormation Template

3. Expected behaviour

Before CFN supported the AWS::CertificateManager::Certificate resource, we created a custom resource to create ACM certificates. Now we would like to replace that custom resource with AWS::CertificateManager::Certificates, and turn off the application backing the custom resource.

4. Suggest specific test cases
N/A

5. Helpful Links to speed up research and evaluation
Importing ACM certificates with CloudFormation [https://docs.aws.amazon.com/acm/latest/userguide/import-certificate.html]
CloudFormation support for provisioning PCA; Private Certificate Authority [https://docs.aws.amazon.com/acm-pca/latest/userguide/PcaWelcome.html]