Function compute_retryable_gas_split 

pub fn compute_retryable_gas_split(
    gas: u64,
    effective_base_fee: U256,
    infra_fee_account: Address,
    min_base_fee: U256,
    arbos_version: u64,
) -> (U256, U256)

Compute the gas payment split between infra and network fee accounts.

Returns (infra_cost, network_cost) where gas_cost = infra_cost + network_cost.