Create and use CppClusterCredentials and CppDnsConfig interfaces for connection

We have a way to bind to the couchbase::core::cluster_credentials (see code here) and couchbase::core::io::dns::dns_config ([see code here|https://github.com/couchbase/couchnode/blob/5884066d27b3c6ed3ede47d992e337a7cdc82213/src/jstocbpp_basic.hpp#L46-L58) objects, but we do not create interfaces in binding.ts. We should create the CppClusterCredentials and CppDnsConfig interfaces to utilize during connect (see code here).