ec2: add AWS::EC2::SubnetNetworkAclAssociation.
ec2: NetworkAclEntry: allow StringLike cidrBlock.
ec2: Subnet: allow StringLike cidrBlock.
ec2: VPC: allow StringLike cidrBlock.
ec2: security rules: allow StringLike cidrIps.
ec2: covariant return type for a property subclass
elasticbeanstalk: Env: allow String versionLabel.
elasticbeanstalk/property: allow Derefable values.
test: add a large Elastic Beanstalk test.