Add automatic DNS lookup functionality to the TCP client builtin

[rdw-software]

In NodeJS, one can connect to a remote (TCP) server using a regular host name. This will trigger a DNS lookup. By default, libuv's API doesn't do this (and understandably so), which means that if it's a desirable feature then this will have to be added on top of the TcpClient module.

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Split off from #61 since I'm not sure if this is really needed. If yes, there could be events like DNS_LOOKUP and DNS_LOOKUP_COMPLETE, or even TCP_HOSTNAME_RESOLVED? Not sure if there's much benefit in having those.