Process configchange event to record minimum gas price and gas parameters

[arhag]

Depends on eosnetworkfoundation/eos-evm-contract#679 and eosnetworkfoundation/silkworm#121.

Capture the config change event (see eosnetworkfoundation/eos-evm-contract#679) and store data provided in event (minimum gas price and the five gas parameters) in data associated to each block (mechanism in eosnetworkfoundation/silkworm#121). Do not use those stored values for anything right now. Just use them to verify that the minimum gas price provided in the config change event changes appropriately and is handled properly with forking changes.

Update integration test to verify the node properly processed blocks with a configchange event.