📌 Add Scripts for Area & Volume of Cylinder and Area of Polygon

[shirshanag]

Description: This PR adds two beginner-friendly Python scripts to the Basic Python Projects repository:

area_volume_cylinder.py

Calculates the volume of a cylinder using the formula π × r² × h

Takes user input for radius and height

Includes basic error handling and comments for clarity

area_of_polygon.py

Computes the area of a regular polygon using the formula (n/2)lr Takes input for radius of sides and length of each side.

These scripts are useful for learners practicing geometric formulas and Python basics like input/output, functions, and math operations.