feat: setup gradle pour lancer l'app et les test, ajout des commandes dans le README.md

app/src/main/java/sudoku/App.java

@@ -0,0 +1,14 @@
+/*
+ * This Java source file was generated by the Gradle 'init' task.
+ */
+package sudoku;
+
+public class App {
+    public String getGreeting() {
+        return "Hello World!";
+    }
+
+    public static void main(String[] args) {
+        System.out.println(new App().getGreeting());
+    }
+}

app/src/test/java/sudoku/AppTest.java

@@ -0,0 +1,17 @@
+/*
+ * This Java source file was generated by the Gradle 'init' task.
+ */
+package sudoku;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class AppTest {
+    @Test
+    public void testExample() {
+        System.out.println("DOING TEST");
+        assertEquals(2 + 2, 4);
+        System.out.println("DONE TEST");   
+    }
+}