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

compiler/testData/loadJava/compiledKotlin/annotations/classes/ClassInClassObject.txt

@@ -7,7 +7,7 @@ internal final annotation class Anno : kotlin.Annotation {
 internal final class Class {
     /*primary*/ public constructor Class()
 
-    internal class object Default {
+    internal default object Default {
         /*primary*/ private constructor Default()
 
         test.Anno() internal final class Nested {