Add tests for class hierarchy incremental recompilation

jps-plugin/testData/incremental/classHierarchyAffected/varianceChanged/D.kt

@@ -0,0 +1,8 @@
+class D<T>(x: T) {
+    companion object {
+        val b = D(B())
+        val c = D(C())
+    }
+
+    var a = A(x)
+}