Add constellation coordinate extraction tutorial

[adithya-ananth]

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[adithya-ananth]

This tutorial demonstrates how to use Astropy to plot constellation boundaries and visualize celestial coordinates. It covers how to:

• Retrieve and use constellation_boundary_moc() from astropy.coordinates
• Plot constellation borders on a sky map using matplotlib and astropy.visualization
• Explore sky coverage with MOC (Multi-Order Coverage) maps

The notebook aims to help users understand how to visualize the layout of constellations and interpret sky maps programmatically.