Add resource providers for Community::DirectConnect::Gateway and Community::DirectConnect::TransitVirtualInterface

[rene84]

We would like to provision DirectConnect resources through Infrastructure as Code, but a few resources are not supported by CloudFormation. For more information as to how and why, see https://www.sentiatechblog.com/deploying-a-transit-gateway-that-integrates-with-a-dx-connection-on-aws-with

[rene84]

Both implemented