adding a chapter on Object-oriented Programming in COBOL

[ahmedEid1]

Signed-off-by: ahmedEid1 ahmedeid6422@gmail.com this PR adds a chapter on OOP in COBOL that has the following content:

• object-oriented programs (130 lines)
  • Intro
  • Wrapping procedure-oriented COBOL programs
  • Notes
  • Example: Design an Account Class
• Class Definition (151 lines)
  • Class Structure
  • Notes
  • Example
• Subclasses Definition (38 lines)
• Defining a factory section (91 lines)
  • Factory structure
  • Defining a factory method
  • Hiding a factory or static method
  • Invoking factory or static methods
• Instance method Definition (213 lines)
  • Structure of instance method definitions
  • Overriding an instance method
  • Overloading an instance method
  • Coding attribute (get and set) methods
  • Notes
  • Example: defining a method
• Client Definition (224 lines)
  • Intro
  • Client structure
  • Creating and initializing instances of classes
  • Invoking methods
  • Comparing and setting object references
  • Notes
  • Example: defining a client
• Structuring OO applications (62 lines)
  • OOP program structure methods
  • Example: COBOL applications that run using the java command

Note: The chapter has no labs.