"Find Usages": add tests for Kotlin usages of Java declarations

idea/testData/findUsages/java/findJavaMethodUsages/JKMethodOverrides.1.kt

@@ -0,0 +1,17 @@
+public open class X: A() {
+    public override fun foo() {
+
+    }
+}
+
+public class Y: X() {
+    public override fun foo() {
+
+    }
+}
+
+public class Z: B() {
+    public override fun foo() {
+
+    }
+}