Update contractKit and celocli to fetch block size differently

[soloseng]

As far as ContractKit or CeloCLI is concerned, it seems that BlockchainParameters wrapper is affected. Since the BlockchainParameters contract is being deprecated on L2, the blockGasLimit and the intrinsicGasForAlternativeFeeCurrency will now be queried on as follows:

• The blockGasLimit is now found on optimism SystemConfig contract. During the L2 migration, we will have to deploy our version of this contract to a different address.

• The intrinsicGasForAlternativeFeeCurrency can be found in the celo FeeCurrencyDirectory contract by calling getCurrencyConfig(token).intrinsicGas

[soloseng]

closed in favor of https://github.com/celo-org/celo-blockchain-planning/issues/314