Detect and suggest DNS name of current machine if possible.

[spotlesscoder]

I have set up my DHCP server to give each host a specific IP according to the MAC address. Also, each of my hosts has a hostname on my internal DNS server. When I was reinstalling Ubuntu on the machine for testing purposes, I was happy that in the step where you should enter the hostname, it automatically detected the hostname I reserved for that IP in my private DNS server and suggested to use that. (Ubuntu 18.04 LTS mini ISO installation media)

I'd like elementary OS installation GUI to do the same (should be easy to achieve with a reverse DNS lookup "nslookup <IP_OF_HOST>").

[danirabbit]

moving to Initial Setup since the hostname that's generated in the Installer is temporary and we have the end user choose their hostname after installation