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/smart/ClassObjectMembers.kt

@@ -1,7 +1,7 @@
 package sample
 
 class K {
-    class object {
+    default object {
         val foo: K = K()
         fun bar(): K = K()
         val x: String = ""

idea/testData/completion/smart/ClassObjectMembersForNullable.kt

@@ -1,7 +1,7 @@
 package sample
 
 class K {
-    class object {
+    default object {
         val foo: K = K()
         fun bar(): K = K()
         val x: String = ""

idea/testData/completion/smart/ClassObjectMembersWithPrefix.kt

@@ -1,7 +1,7 @@
 package sample
 
 class Kool {
-    class object {
+    default object {
         val foo: Kool = Kool()
         fun bar(): Kool = Kool()
     }

idea/testData/completion/smart/InClassObject.kt

@@ -1,5 +1,5 @@
 class C {
-    class object {
+    default object {
         fun foo(): C {
             return <caret>
         }

idea/testData/completion/smart/NoExtensionMethodFromClassObject.kt

@@ -1,5 +1,5 @@
 class X {
-    class object {
+    default object {
         fun String.f(): X = X()
         fun g(): X = X()
     }

idea/testData/completion/smart/functionReference/10.kt

@@ -5,7 +5,7 @@ class C {
         listOf("a").filter(<caret>)
     }
 
-    class object {
+    default object {
         fun staticFoo(s: String): Boolean = true
     }
 }

idea/testData/completion/smart/generics/GenericFunction5.kt

@@ -1,5 +1,5 @@
 class C<T> {
-    class object {
+    default object {
         fun<T> create(t: T): C<T>{}
     }
 }