crypto/noise: Preallocate handshake memory with correct overhead

[lexnv]

Allocate the appropriate amount of memory instead of hardcoding a random value:

litep2p/src/crypto/noise/mod.rs

Lines 252 to 262 in 2a49fd0

	let mut message = BytesMut::zeroed(size as usize);
	io.read_exact(&mut message).await?;
	let mut out = BytesMut::new();
	out.resize(message.len() + 200, 0u8); // TODO: correct overhead
	let NoiseState::Handshake(ref mut noise) = self.noise else {
	tracing::error!(target: LOG_TARGET, "invalid state to read handshake message");
	debug_assert!(false);
	return Err(NegotiationError::StateMismatch);
	};