`sc-chain-spec`: deprecated code removed (#4410)
This PR removes deprecated code: - The `RuntimeGenesisConfig` generic type parameter in `GenericChainSpec` struct. - `ChainSpec::from_genesis` method allowing to create chain-spec using closure providing runtime genesis struct - `GenesisSource::Factory` variant together with no longer needed `GenesisSource`'s generic parameter `G` (which was intended to be a runtime genesis struct). https://github.com/paritytech/polkadot-sdk/blob/17b56fae2d976a3df87f34076875de8c26da0355/substrate/client/chain-spec/src/chain_spec.rs#L559-L563