feat: add sanity tests for Args Default impls

[Rjected]

ref #5658 (review)

added tests accordingly, this was a very good idea, since the GasPriceOracleArgs::default impl just set everyting to None

[mattsse]

lgtm,
can do constants issue as good first issue

[mattsse]

let's open an issue to replace those with constants

[mattsse]

we should use the config's default here

reth/crates/payload/basic/src/lib.rs

Lines 306 to 321 in 5ac4a3d

	impl Default for BasicPayloadJobGeneratorConfig {
	fn default() -> Self {
	let mut extradata = BytesMut::new();
	RETH_CLIENT_VERSION.as_bytes().encode(&mut extradata);
	Self {
	extradata: extradata.freeze().into(),
	max_gas_limit: ETHEREUM_BLOCK_GAS_LIMIT,
	interval: Duration::from_secs(1),
	// 12s slot time
	deadline: SLOT_DURATION,
	max_payload_tasks: 3,
	#[cfg(feature = "optimism")]
	compute_pending_block: false,
	}
	}
	}