add test for isWarm

Author: madsodgaard

Samples/JExtractJNISampleApp/src/test/java/com/example/swift/MySwiftClassTest.java

@@ -111,5 +111,11 @@ void mutableDividedByTwo() {
         }
     }
 
-
+    @Test
+    void isWarm() {
+        try (var arena = new ConfinedSwiftMemorySession()) {
+            MySwiftClass c = MySwiftClass.init(20, 10, arena);
+            assertFalse(c.isWarm());
+        }
+    }
 }