AWS::RDS::DBClusterEndpoint

AWS::RDS::DBClusterEndpoint - can create resource via API, but not via CloudFormation

**Scope of request**

Add support for Aurora custom [cluster endpoints](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/rds/create-db-cluster-endpoint.html).

**Expected behavior**

Have the same options as the [API](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_CreateDBClusterEndpoint.html).
During update the resource should always _require replacement_. This is because updates to custom endpoints cause gaps in DNS resolution of the endpoint updated.

**Category**

DB - RDS Aurora

Start with the AWS CLI create-db-cluster-endpoint reference and the CreateDBClusterEndpoint API documentation linked in the issue, then inspect this repository's existing RDS Aurora coverage entries. No repository files or tests are named. Done means the resource supports the API's options and updates require replacement, with the coverage status recorded here.

Written by the indexing model from the issue text.