feat(rust/catalyst-voting): Jormungandr tx building

[Mr-Leshiy]

Description

Added functionally to build a signed transaction v1::Tx, generate a proof and as well to verify all of it.

Related Issue(s)

Closes #55

Description of Changes

• Added crypto::ed25519 signing functionality
• Refactored election keys to the new structs ElectionPublicKey and ElectionSecretKey.
• Added v1::Tx::new_public and v1::Tx::new_private functions to build and sign a valid transaction.
• Added Blake2b256Hasher hash function.
• Updated v1::Tx decoding with the witness part.
• Added v1::Tx::verify_proof and v1::Tx::verify_signature methods.
• Added v1::Tx::public_choice and v1::Tx::private_choice methods to retrieve an original voting choice.
• Added new functions with default rng (named *_with_default_rng) to the corresponding one which takes rng as an argument

[github-actions]

✅ Test Report | ${\color{lightgreen}Pass: 210/210}$ | ${\color{red}Fail: 0/210}$ |

[stevenj]

LGTM