Kotlin: Add test case for ::class type check in equals

Author: tamasvajk

java/ql/test/kotlin/query-tests/MissingInstanceofInEquals/MissingInstanceofInEquals.expected

@@ -0,0 +1 @@
+| Test.kt:10:14:12:5 | equals | This 'equals()' method does not check argument type. |

java/ql/test/kotlin/query-tests/MissingInstanceofInEquals/Test.kt

@@ -5,3 +5,9 @@ data class E(val x: Int) {
         return (other as? E)?.x == this.x
     }
 }
+
+data class F(val x: Int) {
+    override fun equals(other: Any?): Boolean {
+        return other != null && other::class == this::class
+    }
+}