Add GenesisConfig for Millau and Rialto Runtimes (#401)

* Add Rialto as a target for the Millau node

* Rename Rialto module to Rialto-PoA

This will reduce confusion as the Millau runtime has a
Rialto module as well which refers to the Substrate chain.

* Add Millau as a target for the Rialto node

* Be more explicit about Rialto PoA related code

* Missed some name changes in the Ethereum PoA relay

* Re-export Substrate pallet structs used by node

* Remove `first_scheduled_change` of Millau in Rialto node

* Make Millau's genesis config for Rialto bridge more accurate

* Set initial header for Millau config

* Update initial Millau authorities

Co-authored-by: Svyatoslav Nikolsky <[email protected]>

* RustFmt Millau authorities

Co-authored-by: Svyatoslav Nikolsky <[email protected]>