genesis: introduce a new ValidatorBuilder

Introduce a new ValidatorBuilder type for use in creating new validator
networks. The intent of this new config builder is to make clearer the
genesis creation process as well as ensure the environement for each
validator is closer to production (e.g. the root key shouldn't exist in
each validator's secure storage).

For now this builder tries to mimic some of the existing behavior of the
old builder (e.g. treasury and root keys are the same) but the intent is
that this is only temporary until forge is operational.

config/management/genesis/src/lib.rs

@@ -8,6 +8,7 @@ pub mod command;
 mod genesis;
 mod key;
 pub mod layout;
+pub mod validator_builder;
 mod validator_config;
 mod validator_operator;
 mod verify;