Add option for Single vs Compared Visualization

Now we have combined visualizer that shows side-by-side animations of two sorting algorithms. It would be beneficial to add a separate option that lets users choose between single and a compared visualization mode

### Proposed Implementation:

- Command-line Flag or Config Option:
- [ ] Add an option (e.g., a command-line flag like --mode single or --mode combined) in main.py to let users choose the desired visualization mode.

- Separate Visualizer Classes:

- [x] Maintain the existing CombinedVisualizer for compared visualization.

- [ ] Create a new SingleVisualizer class to handle visualizations for a single sorting algorithm.

- Integration in main.py:

- [ ] Modify main.py so that it checks the chosen mode and instantiates either the SingleVisualizer (if the mode is single) or the CombinedVisualizer (if the mode is combined).