Figure out bincode Decode/Encode interop with serde

[VictorKoenders]

Currently bincode 2 only allows either Decode/Encode, or serde's traits. It would be nice to have a way to use serde types while using Decode/Encode

Some ideas:

• Add an #[serde_interop] attribute to bincode_derive
• Add a WithSerde<T> that implements Decode/Encode
• Disable the default impl for Decode/Encode and replace it with something like:
  • impl Decode for T where T: Deserialize
  • impl Encode for T where T: Serialize