Add containers project with CMake setup and array-related functionality

- Implement `printArrayAtPosition` in `functions.cpp` with input validation.
- Created `main.cpp` to demonstrate array operations using C arrays and `std::vector`.
- Updated `ClassA` and `IComparable` with constructors, destructors, and deep copy logic.
- Adjusted IntelliJ project configuration for new containers module.

cpp/containers/main.cpp

@@ -0,0 +1,39 @@
+#include <iostream>
+#include <vector>
+
+#include "functions.h"
+
+int main(int argc, const char* argv[]) {
+    // C array
+    int numbers[5] = {1, 2, 3, 4, 5}; // stack array
+    const int count = 10;
+    int numbers2[count];
+
+    int count2 = 10;
+    int* numbers3 = new int[count2]; // heap array
+    delete[] numbers3;
+    numbers3 = nullptr;
+
+    // numbers[10] = 100;
+    std::cout << "size of numbers: " << sizeof(numbers) << std::endl;
+
+    printArrayAtPosition(numbers, 19);
+
+    // vector
+    std::vector<int> v = {1, 2, 3, 4, 5};
+
+    std::cout << "size of v: " << v.size() << "/" << v.capacity() << std::endl;
+
+    v.push_back(6);
+
+    std::cout << "size of v: " << v.size() << "/" << v.capacity() << std::endl;
+
+    // v[20] = 100;
+    printArrayAtPosition(v.data(), 2);
+
+    v.pop_back();
+
+    std::cout << "size of v: " << v.size() << "/" << v.capacity() << std::endl;
+
+    return 0;
+}