Add common research notebook templates for charting

[AlexCatarino]

Summary

• Adds project-templates/csharp/common/research.ipynb demonstrating Plotly.NET chart types: candlestick, line, scatter, heat map, 3D.
• Adds project-templates/python/common/research.ipynb demonstrating Matplotlib chart types: candlestick, line, scatter, histogram, bar, heat map, pie, 3D.
• Each notebook opens with a one-line intro and shares a single preparation block (XLF / COF / GS / JPM / WFC, daily, 2021).

Test plan

• Open the C# notebook on QC Cloud, run all cells, confirm each chart renders.
• Open the Python notebook on QC Cloud, run all cells, confirm each chart renders.