Add End-to-End Encryption for Clipboard Data Transmission

# Issue Description
Currently, the r_clip tool effectively synchronizes clipboard content between a remote server and a local machine using a reverse TCP connection. However, the clipboard data is transmitted in plaintext over the network, which could pose security risks, especially when handling sensitive information.

# Proposed Enhancement
To enhance the security of r_clip, I propose implementing end-to-end encryption for the clipboard data transmitted between the server and the client. This would ensure that clipboard data remains confidential and secure from potential eavesdropping or man-in-the-middle attacks.

# Suggested Approach
- Research and decide on an appropriate encryption protocol (e.g., AES, RSA).
- Implement encryption of clipboard data on the server side before transmission.
- Implement decryption of the received data on the client side.
- Ensure that the encryption/decryption process is efficient and doesn't significantly impact the tool's performance.
- (Optional) Implement key exchange mechanism for shared secret keys or public/private key pairs, depending on the chosen encryption method.

# Impact
- Security: Significantly increases the security of data transmission in r_clip.
- User Trust: Builds user trust in using r_clip for copying sensitive information.
- Performance: Need to ensure that the added encryption layer does not introduce significant performance overhead.