Store parent chain's gateway actor ID on subnet chain

[karlem]

Are we allowed to override parent_subnet_id, f3_network_name, gateway_actor_id/gateway_eth_address, and subnet_id with a local config? Are they stored in the chain state at all?

Originally posted by @sergefdrv in #1457 (comment)

Also see #1469 (comment)

[linear]

IPC-335