feat: adding vehicle classes and main program

The classes are on Vehicles folder and being used in Main.java file.

README.md

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+# Java Classes
+
+This project contains how Java classes can extend from a parent class and how to be implemented in different files.
+The main class is `Main.java`, where the class Sport, SUV and Hybrid are being used and extend from Vehicle class.
+
+
+## Diagram
+
+```mermaid
+classDiagram
+
+class Vehicle {
+    -String make
+    -String model
+    +int doors
+    -int year
+    +EngineType typeOfEngine
+    +Vehicle(String make, String model, int year)
+    +EngineType getManualEngineType()
+    +EngineType getAutomaticEngineType()
+    +String getMake()
+    +EngineType getTypeOfEngine()
+    +int getDoors()
+    +String getModel()
+    +int getYear()
+    +String forward()
+    +String reverse()
+    +String stop()
+}
+
+class EngineType {
+    <<enumeration>>
+    AUTOMATIC
+    MANUAL
+}
+
+class SUV {
+    -boolean fourWheelDrive
+    +SUV(String make, String model, int year, boolean fourWheelDrive)
+    +boolean hasFourWheelDrive()
+    +String forward()
+    +String reverse()
+    +String stop()
+    +String engageFourWheelDrive()
+}
+
+class Sport {
+    -int topSpeed
+    -GearNumbers gear
+    +Sport(String make, String model, int year, int topSpeed)
+    -GearNumbers setGear(int gear)
+    +double getTopSpeed()
+    +String forward()
+    +String reverse()
+    +String stop()
+    +String drift()
+    +String nitroBoost()
+    +void changeGearUp()
+    +GearNumbers getGear()
+    +void changeGearDown()
+    +void setGearToNeutral()
+}
+
+class GearNumbers {
+    <<enumeration>>
+    R
+    N
+    GEAR_1
+    GEAR_2
+    GEAR_3
+    GEAR_4
+    GEAR_5
+    GEAR_6
+}
+
+class Hybrid {
+    -double batteryCapacity
+    +Hybrid(String make, String model, int year, double batteryCapacity)
+    +double getBatteryCapacity()
+    +String forward()
+    +String reverse()
+    +String stop()
+}
+
+Vehicle <|-- SUV
+Vehicle <|-- Sport
+Vehicle <|-- Hybrid
+Vehicle *-- EngineType
+Sport *-- GearNumbers
+```