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/resolve/referenceInJava/ClassObjectField.java

@@ -4,4 +4,4 @@ public class ClassObjectField {
     }
 }
 
-// REF: class object of (k).ClassWithClassObject
+// REF: default object of (k).ClassWithClassObject

idea/testData/resolve/referenceInJava/DeprecatedClassObjectField.java

@@ -4,4 +4,4 @@ public class ClassObjectField {
     }
 }
 
-// REF: class object of (k).ClassWithClassObject
+// REF: default object of (k).ClassWithClassObject

idea/testData/resolve/referenceInJava/dependencies.kt

@@ -16,7 +16,7 @@ public fun topLevelFun() {
 }
 
 public class ClassWithClassObject {
-    class object {
+    default object {
         fun f() = 1
     }
 }
@@ -26,7 +26,7 @@ public object KotlinObject {
 }
 
 public trait StaticFieldInClassObjectInTrait {
-    class object {
+    default object {
         public val XX: String = "xx"
     }
 }