Implement build_block for EthApi using the PayloadBuilder

[mattsse]

Describe the feature

we currently have a default impl for

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

Line 216 in 5c655e4

fn build_block(

this uses redundant block building code, we can instead leverage the PayloadBuilder for this by

1. remove the default impl of build_block
2. impl it here

   reth/crates/rpc/rpc/src/eth/helpers/pending_block.rs

   Lines 17 to 20 in 5c655e4

   	for EthApi<Provider, Pool, Network, EvmConfig>
   	where
   	Self: SpawnBlocking
   	+ RpcNodeCore<

3. and also restrict the RpcNodeCore::PayloadBuilder type

this is similar to

reth/crates/engine/local/src/payload.rs

Lines 30 to 42 in 5c655e4

	EthPayloadAttributes {
	timestamp,
	prev_randao: B256::random(),
	suggested_fee_recipient: Address::random(),
	withdrawals: self
	.chain_spec
	.is_shanghai_active_at_timestamp(timestamp)
	.then(Default::default),
	parent_beacon_block_root: self
	.chain_spec
	.is_cancun_active_at_timestamp(timestamp)
	.then(B256::random),
	}

where we create attributes and leverage the payload builder API to resolve the payload

reth/crates/payload/primitives/src/traits.rs

Line 24 in 5c655e4

fn send_new_payload(

reth/crates/payload/primitives/src/traits.rs

Lines 35 to 39 in 5c655e4

	/// Resolves the payload job and returns the best payload that has been built so far.
	async fn resolve_kind(
	&self,
	id: PayloadId,
	kind: PayloadKind,

Additional context

No response

[SkandaBhat]

@mattsse can I work on this?