integrate sphinx for onion message obfuscation

[doitian]

See more in the sphinx implementation repo https://github.com/cryptape/fiber-sphinx

What's changed?

• Replace

  fiber/src/fiber/types.rs

  Lines 2718 to 2737 in 5685f40

  	// TODO: replace this with real OnionPacket implementation
  	#[serde_as]
  	#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
  	pub struct OnionInfo {
  	pub payment_hash: Hash256,
  	// this is only specified in the last hop in the keysend mode
  	pub preimage: Option<Hash256>,
  	pub tlc_hash_algorithm: HashAlgorithm,
  	pub amount: u128,
  	pub expiry: u64,
  	pub next_hop: Option<Pubkey>,
  	#[serde_as(as = "Option<EntityHex>")]
  	pub channel_outpoint: Option<OutPoint>,
  	}
  	// TODO: replace this with real OnionPacket implementation
  	#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
  	pub struct OnionPacket {
  	pub hop_data: Vec<OnionInfo>,
  	}

  with sphinx

[chenyukang]

or we passing the private_key to channel state when creating channel actor, i'm not sure which way is better.

[chenyukang]

better comment style in line 151~152 .