✨ add hostname

[lvenier]

Agent version	Docker API Version
1.X	1.43

In the docker api it is possible to add hostname to populate the host file :

ExtraHosts	
Array of strings
A list of hostnames/IP mappings to add to the container's /etc/hosts file. Specified in the form ["hostname:IP"].

It would be good to allow that configuration when we edit a container.
I suggest to have an extra field extra_host in the json with the following format :
extra_host: ["hostname1:IP1","hostname2:IP2",....] defaulted as []