Rewrite tasks #3 and #4 using classes

[romaneo]

Based on #3 and #4

Implement the same logic but create separate classes for each geometrical object

Programm limitation:

• Create a simple class, do not use inheritance (and any other OOP principles)
• There is no need to create a forever loop for a program menu

Programm requirements:

• You may create properties for setting up the input data for your classes
• You may add the constructors
• You have to follow best practices to separate private/public fields/properties

(*)Programm enhancements:

• Feel free to add some other input parameters for your classes or more geometrical objects and calculate more properties. (e.g. create a class Trapezoid, enter the value of bases, calculate a Midsegment) http://ua.onlinemschool.com/math/formula/trapezium/

Learning materials:

• https://docs.microsoft.com/ru-ru/dotnet/csharp/programming-guide/classes-and-structs/constructors
• https://docs.microsoft.com/ru-ru/dotnet/csharp/programming-guide/classes-and-structs/using-constructors
• https://docs.microsoft.com/ru-ru/dotnet/csharp/programming-guide/classes-and-structs/instance-constructors

[romaneo]

@marikalmuk Please merge to main and close the issue