Create explainable code-diff graphs

[nikivanstein]

To understand where a good solution is coming from, it would be good if we can visualize the path to this solution in terms of visualizing the code diffs.

[nikivanstein]

#54

[anantashahane]

Got it working for a single comparison today, learning about Streamlit app state management to for complete comparison.

[anantashahane]

Added tab view, the show every parent, child mutation, requires one additional dependency in: https://github.com/LinXueyuanStdio/streamlit-diff-viewer