Add Linea as known network

[m4sterbunny]

Linea is now one of the known networks.
So you can run besu --network=linea for linea mainnet, and besu --network=linea_sepolia for linea sepolia.

Will impact besu docs https://besu.hyperledger.org/public-networks/get-started/connect
maybe we want a separate section there for linea specifically? the existing pages are eth mainnet/testnet

May also impact Linea docs: where it talks about how to run linea with besu, this replaces "download the genesis file and set the chain id"

per besu-docs/docs/public-networks/reference/cli/options.md: You can't use the --network and --genesis-file options at the same time.

Per PR hyperledger/besu#9436

[m4sterbunny]

Need to decide:
[] /public-networks/get-started/start-node expand the set to say: a. Nodes can connect to Ethereum Mainnet and public testnets AND the Linea L2 OR b. separate docs into L1 and L2 (IMO a)
[] /public-networks/get-started/connect Connect to a network currently nests > Connect to Mainnet and Connect to a testnet. a. This may need to be reorged to cover Ethereum L1 vs L2 --> specifically: suspect that Linea consensys clients will not be the same set as the L1 clients. or b. Mainnet page need to cover Ethereum and Linea.

This PR touches many of the pages that detail networks, may be helpful: #1865

[bgravenorst]

What are your thoughts on keeping the Linea content to minimum here? E.g we can just update the --networks option, and add mentions in a few places about Linea support with links to the content in https://docs.linea.build/get-started/how-to/run-a-node

I'd assume any user wanting to run a Linea node would go to the Linea docs instead anyway. We may need to reach out regarding updating the Linea node content since it appears there may be updates happening there.

[alexandratran]

Agree with @bgravenorst that we should not add too much Linea guidance, as that should be maintained solely on the Linea doc site. There are several more places besides --network that we might need to mention Linea support:

• Landing page: https://besu.hyperledger.org/public-networks
• Start Besu: https://besu.hyperledger.org/public-networks/get-started/start-node (the ETH testnets can probably all be consolidated into one section with multiple code tabs)
• Network ID and chain ID: https://besu.hyperledger.org/public-networks/concepts/network-and-chain-id
• net_version: https://besu.hyperledger.org/public-networks/reference/api#net_version
• (Maybe) EVM tool --chain: https://besu.hyperledger.org/public-networks/reference/evm-tool#chain