feat(flashblocks): support eth_getBlockTransactionCount for flashblocks

[sieniven]

Summary

• Enable support for eth_getBlockTransactionCountByNumber and eth_getBlockTransactionCountByHash apis for flashblock
• Note that we duplicate the logic from the default trait implementation in the underlying helper method to contain the flashblocks implementation inside the optimism ethapi

[mattsse]

that makes sense but should we perhaps change

reth/crates/rpc/rpc-eth-api/src/helpers/block.rs

Lines 77 to 83 in 1752d6f

	if block_id.is_pending() {
	// Pending block can be fetched directly without need for caching
	return Ok(self
	.provider()
	.pending_block()
	.map_err(Self::Error::from_eth_err)?
	.map(|block| block.body().transaction_count()));

to just

reth/crates/rpc/rpc-eth-api/src/helpers/block.rs

Lines 189 to 192 in 1752d6f

	// If no pending block from provider, build the pending block locally.
	if let Some(pending) = self.local_pending_block().await? {
	return Ok(Some((pending.block, pending.receipts)));
	}

instead?

[limyeechern]

Hi @mattsse, we have made changes according to your suggestion. We now do not duplicate the logic but update the block_transaction_count function in the EthBlocks trait

[mattsse]

ah we need to keep this check actually