restructure: crate

[brech1]

Description

This PR introduces a restructuring of the semaphore-rs crate.

Changes

• Updates to Rust 2024 edition and arkworks cryptographic libraries
• Adds a Baby Jubjub curve implementation adhering to EIP-2494 specs
• Adds general error handling with specific error types
• Implements identity and group modules
• Adds integration tests for identity operations

Related Issue(s)

• Resolves Identity implementation #4

Checklist

• I have read and understand the contributor guidelines and code of conduct.
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have run cargo fmt without getting any errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[vivianjeng]

could you keep these two files,
we still need this prover structure