add class intConstant to ast

src/main/java/abstractSyntaxTree/Expression/IntConstantExpression.java

@@ -0,0 +1,11 @@
+package abstractSyntaxTree.Expression;
+
+import TypeCheck.AbstractType;
+
+public class IntConstantExpression extends AbstractType implements IExpression{
+    public int value;
+
+    public IntConstantExpression(int value) {
+        this.value = value;
+    }
+}