Add support for Ed25519 key generation

[AlexiaChen]

Fixes #6

Add support for Ed25519 key generation in the MPVSS implementation.

• src/mpvss.rs

  • Import ed25519_dalek crate for Ed25519 key generation.
  • Add KeyAlgorithm enum to represent key generation algorithms.
  • Update MPVSS struct to include key_algorithm field.
  • Add generate_ed25519_keypair function to generate Ed25519 key pairs.
  • Update generate_private_key and generate_public_key functions to support both original and Ed25519 algorithms.

• README.md

  • Update "Initialization" section to include Ed25519 key generation.
  • Add a note about Ed25519 key generation in the "In the futures" section.

• tests/mpvss_tests.rs

  • Add test_ed25519_key_generation function to verify Ed25519 key generation.

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[AlexiaChen]

Just test github copilot workspace to plan impl and create PR, seems it not good as I want..... So closed it

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tests/mpvss_tests.rs:79

• Ensure that the new functionality is covered by tests, including integration with the MPVSS struct.

let (secret_key, public_key) = generate_ed25519_keypair();