Use descriptors for reflection on class properties

- use ConcurrentHashMap as a cache of class loaders to module descriptors
- KClassImpl now has a lazy class descriptor and it manages property creation
  by looking (also lazily) for the property descriptor in the corresponding
  scope
- since deserialized descriptors have full information about where a JVM symbol
  is located and what signature it has, new tests will begin to pass where
  Kotlin model and Java reflection model differ, see classObjectVar.kt

compiler/tests/org/jetbrains/kotlin/codegen/generated/BlackBoxWithStdlibCodegenTestGenerated.java

@@ -741,6 +741,12 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
                 JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/boxWithStdlib/callableReference/property"), Pattern.compile("^(.+)\\.kt$"), true);
             }
 
+            @TestMetadata("classObjectVar.kt")
+            public void testClassObjectVar() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/callableReference/property/classObjectVar.kt");
+                doTestWithStdlib(fileName);
+            }
+
             @TestMetadata("delegated.kt")
             public void testDelegated() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/callableReference/property/delegated.kt");