Implement AES for enhanced security

[Moltivie]

This PR adds end-to-end encryption for all commands and responses in ConvoC2.

Features Added

• Implemented AES-256-GCM encryption for commands embedded in Teams messages
• Added encryption for command outputs returned via webhooks
• Created a deterministic key derivation system that requires no separate key exchange
• Implemented 24-hour automatic key rotation for increased security
• Added backward compatibility to support both encrypted and plaintext commands

[cxnturi0n]

Thank you for your PR! I'll start reviewing it now.

[Moltivie]

Thank you for your PR! I'll start reviewing it now.

Hey! Have you had time to review the PR? Do not hesitate for any questions :)