Add Enhanced Interactive C++ Program for Greeting and Arithmetic Operations

[MeghanaKatraju31]

This Pull Request introduces an enhanced C++ program that includes user interaction, input validation, and arithmetic operations. The following features and improvements have been implemented:

Greeting Message: The program starts by printing "Hello, World!" to the console.
User Input for Name: Prompts the user to enter their name, allowing spaces in the input by using std::getline.
Personalized Greeting: Greets the user with their entered name.
Input Validation for Numbers: Asks the user for two integers, with validation to handle invalid inputs and prompt the user to enter correct values.
Arithmetic Operation: Computes the sum of the two entered integers.
Display Results: Outputs the result of the addition to the console.
Key Changes:

Input Handling: Improved user input handling by using std::getline for names and robust validation for numeric inputs.
Error Handling: Added loops to ensure the user inputs valid integers and handle incorrect inputs gracefully