Added Comprehensive Cryptographic Tests

This PR implements a complete suite of cryptographic tests for the Secret Network enclave's shared crypto module. We've addressed the TODO comment in the crypto library by adding proper encryption tests and other critical cryptographic function tests. The implementation includes AES-SIV encryption/decryption tests with both test vectors and roundtrip verification, ensuring that the encryption functionality works correctly with various inputs including empty additional authenticated data. We've also added SHA-256 hash tests with standard test vectors to verify the integrity of the hashing implementation. HMAC-SHA256 tests were implemented to confirm that the message authentication code functionality produces consistent results with the same inputs while properly differing when keys or messages change. Additionally, we've added Ed25519 digital signature tests that verify key generation, signing, and verification processes, including negative tests that ensure signature verification fails appropriately with modified messages or different keys. All tests are now registered in the main test runner and will execute when tests are run with the "test" feature enabled, providing comprehensive test coverage for the cryptographic foundations of the Secret Network.