Add server initialization command

[mabdh]

Is your feature request related to a problem? Please describe.
There is no config sample or guide what config should we use when we try dex. It is hard for a new person to onboard to this project.

Describe the solution you'd like
Create a command to generate config dex server init to generate config.yaml or x.yaml file. Other goto projects (e.g. shield, siren) already had this feature.