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/fromLoadJava/ClassObject.txt

@@ -2,7 +2,7 @@ package test
 
 internal trait TheTrait {
 
-    internal class object Default {
+    internal default object Default {
         /*primary*/ private constructor Default()
     }
 }