Move holocene next block base fee handling into opChainspec

[mattsse]

Describe the feature

after #16927 we can move

reth/crates/optimism/consensus/src/validation/mod.rs

Lines 189 to 206 in ad8fec4

	/// Read from parent to determine the base fee for the next block
	///
	/// See also [Base fee computation](https://github.com/ethereum-optimism/specs/blob/main/specs/protocol/holocene/exec-engine.md#base-fee-computation)
	pub fn next_block_base_fee(
	chain_spec: impl EthChainSpec + OpHardforks,
	parent: impl BlockHeader,
	timestamp: u64,
	) -> Result<u64, EIP1559ParamError> {
	// If we are in the Holocene, we need to use the base fee params
	// from the parent block's extra data.
	// Else, use the base fee params (default values) from chainspec
	if chain_spec.is_holocene_active_at_timestamp(parent.timestamp()) {
	Ok(decode_holocene_base_fee(chain_spec, parent, timestamp)?)
	} else {
	Ok(chain_spec.next_block_base_fee(&parent, timestamp).unwrap_or_default())
	}
	}

into next_block_base_fee of OpChainSpec so that post holocene decoding is respected

TODO

• Call this fn from opchainspec's fn

Additional context

No response

[rose2221]

would like to work on this! Could you assign it to me?

[mattsse]

assigned ty