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/completion/weighers/smart/NoNameSimilarityForQualifier.kt

@@ -1,5 +1,5 @@
 class Name {
-    class object {
+    default object {
         fun create(): Name = Name()
     }
 }

idea/testData/completion/weighers/smart/NullableExpected.kt

@@ -1,7 +1,7 @@
 var global: C = C()
 
 abstract class C {
-    class object {
+    default object {
         val INSTANCE = C()
     }
 }

idea/testData/completion/weighers/smart/SmartPriority2.kt

@@ -3,7 +3,7 @@ var nullableX: C? = null
 var nullableFoo: C? = null
 
 abstract class C {
-    class object {
+    default object {
         val INSTANCE_X = C()
         val INSTANCE_FOO = C()
     }