Change key generation to use openssl_pbkdf2 for improved performance

• Updated the key generation function to use openssl_pbkdf2 with 1000 iterations
• instead of hash_pbkdf2. This change improves performance while maintaining
• compatibility with the existing encryption and decryption processes.

Version 1.0.0 of ASCrypto library

• Added core functionality for encryption and decryption using a password
• Implemented AES-128-CBC as default cipher method
• Included methods for key generation and error handling
• Provided usage examples in README
• Implemented HMAC-based integrity check to ensure data integrity during encryption and decryption.