benchmarking

To add a new method for benchmarking:

1. Create a file method_steganography.py
2. Create a class that extends the SteganographyMethod class from steganography_interface.py.
3. Import the class into benchmark.py and add its entry in the array:

steganography_methods: List[SteganographyMethod] = [
        QRCodeSteganography(),
        MethodSteganography()
    ]

4. Run python3 benchmark.py