Identity implementation

[KimiWu123]

Description

To implement Identity functions.

Resources

• interface: https://github.com/semaphore-protocol/semaphore/blob/main/packages/identity/src/index.ts
• baby-jubjub and EdDSA-Poseidon: not supported by zk-kit.rs.
  • Have a issue: Create a crate for EdDSA Poseidon (BabyJubjub curve) privacy-scaling-explorations/zk-kit.rust#9
• Adria had an implementation