Add a dumpconfig subcommand

[elmattic]

Issue summary

We need a dumpconfig subcommand together with the cli parameters you would like to use.

Forest creates a config file for you which you can use, rather than creating it yourself.

e.g.
forest --network calibnet --rpc-port 1235 dumpconfig > config.toml

Other information and links

Not sure if we want to pick the settings of --config into account (I would say yes).
So check what other blockchain clients are doing.