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/ClassObject.kt

@@ -3,5 +3,5 @@ package test
 annotation class Anno
 
 class Class {
-    Anno class object
+    Anno default object
 }