Make a dataclass for apply_body's return value

[SamWilsn]

It's getting really unwieldy:

execution-specs/src/ethereum/london/fork.py

Lines 492 to 504 in cd9b7d6

	def apply_body(
	state: State,
	block_hashes: List[Hash32],
	coinbase: Address,
	block_number: Uint,
	base_fee_per_gas: Uint,
	block_gas_limit: Uint,
	block_time: U256,
	block_difficulty: Uint,
	transactions: Tuple[Union[LegacyTransaction, Bytes], ...],
	ommers: Tuple[Header, ...],
	chain_id: U64,
	) -> Tuple[Uint, Root, Root, Bloom, State]:

Originally posted by @SamWilsn in #867 (comment)