Set base_fee_per_gas field when creating EVM blocks

[elmato]

Depends on eosnetworkfoundation/eos-evm-contract#697 and eosnetworkfoundation/silkworm#138

Adjust evmtx_v0 type (make same as contract).

In generate_new_evm_block() the base_fee_per_gas value should be copied over from the last to the new block.

In the block_conversion_plugin when deserializing an evmtx_v0 the base_fee_per_gas field of the event should overwrite whatever is in the current block base_fee_per_gas field validating that it remains constant on each generated EVM block.

Also bring in updated silkworm submodule (to include the changes from eosnetworkfoundation/silkworm#138) so that the node is consistent in behavior with the contract that is updated with the changes of eosnetworkfoundation/eos-evm-contract#696.