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/propertiesWithoutBackingFields/ClassObject.kt

@@ -3,7 +3,7 @@ package test
 annotation class Anno
 
 class Class {
-    class object {
+    default object {
         [Anno] val property: Int
             get() = 42
     }

compiler/testData/loadJava/compiledKotlin/annotations/propertiesWithoutBackingFields/ClassObject.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 val property: kotlin.Int
             internal final fun <get-property>(): kotlin.Int

compiler/testData/loadJava/compiledKotlin/annotations/propertiesWithoutBackingFields/TraitClassObject.kt

@@ -3,7 +3,7 @@ package test
 annotation class Anno
 
 trait Trait {
-    class object {
+    default object {
         [Anno] val property: Int
             get() = 42
     }

compiler/testData/loadJava/compiledKotlin/annotations/propertiesWithoutBackingFields/TraitClassObject.txt

@@ -6,7 +6,7 @@ internal final annotation class Anno : kotlin.Annotation {
 
 internal trait Trait {
 
-    internal class object Default {
+    internal default object Default {
         /*primary*/ private constructor Default()
         test.Anno() internal final val property: kotlin.Int
             internal final fun <get-property>(): kotlin.Int