Provide a way to configure timestamp on genesis for Revive dev-node

[mordamax]

https://www.diffchecker.com/kOtI6iDc/

Problem:
on anvil and hardhat dev node (EDR) the genesis block (0x0) starts with timestamp of when the node has been started
In our dev-node and in geth - the genesis block has timestamp: 0 but, I didn't find a way to override this behaviour for manual seal consensus

as @pgherveou suggested in DMs - pallet-timestamp should be updated so that it can be configured with a custom timestamp at genesis