Replace 'class object' with 'default object' in renderers and test data

Includes changes to decompiled text
Old syntax is used in builtins and project code for now

idea/testData/decompiler/stubBuilder/Annotations/Annotations.kt

@@ -17,7 +17,7 @@ a public class Annotations private [a] (private [a] val c1: Int, [a] val c2: Int
         [a] private set
 
 
-    private b(E.E2) class object {
+    private b(E.E2) default object {
 
     }
 }

idea/testData/decompiler/stubBuilder/ClassObject/ClassObject.kt

@@ -6,7 +6,7 @@ class ClassObject {
 
     val c = 1
 
-    public class object {
+    public default object {
         val j = 0
         fun z() = 0
 
@@ -20,11 +20,11 @@ class ClassObject {
 
 
     class B {
-        class object {
+        default object {
             class C {
-                class object {
+                default object {
                     class D {
-                        class object {
+                        default object {
                             val i = 3
                             fun f() {
                             }

idea/testData/decompiler/stubBuilder/DependencyOnNestedClasses/Dependency.kt

@@ -8,7 +8,7 @@ class D {
         class Nested
     }
 
-    class object {
+    default object {
         class NestedInClassObject
     }
 }

idea/testData/decompiler/stubBuilder/Enum/Enum.kt

@@ -7,7 +7,7 @@ enum class Enum {
 
     open fun f() = 3
 
-    class object {
+    default object {
         val c: Int = 1
     }
 }