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/codegen/box/objects/flist.kt

@@ -3,7 +3,7 @@ public abstract class FList<T>() {
     public abstract val tail: FList<T>
     public abstract val empty: Boolean
 
-    class object {
+    default object {
         val emptyFList = object: FList<Any>() {
             public override val head: Any
                 get() = throw UnsupportedOperationException();

compiler/testData/codegen/box/objects/kt1047.kt

@@ -2,7 +2,7 @@ public open class Test() {
     open public fun test() : Unit {
         System.out?.println(hello)
     }
-    class object {
+    default object {
         private val hello : String? = "Hello"
     }
 }

compiler/testData/codegen/box/objects/kt2719.kt

@@ -1,5 +1,5 @@
 class Clazz {
-    class object {
+    default object {
         val a = object {
             fun run(x: String) = x
         }

compiler/testData/codegen/box/objects/kt535.kt

@@ -3,7 +3,7 @@ class Identifier<T>(t : T?, myHasDollar : Boolean) {
 
     public fun getName() : T? { return myT }
 
-    class object {
+    default object {
         open public fun init<T>(name : T?) : Identifier<T> {
             val __ = Identifier<T>(name, false)
             return __

compiler/testData/codegen/box/objects/kt560.kt

@@ -4,7 +4,7 @@ import java.io.*
 
 open class AllEvenNum() {
 
-    class object {
+    default object {
         open public fun main(args : Array<String?>?) : Unit {
             var i : Int = 1
             while ((i <= 100)) {

compiler/testData/codegen/box/objects/kt640.kt

@@ -14,7 +14,7 @@ public open class Identifier<T>(myName : T?, myHasDollar : Boolean) {
         return myName
     }
 
-    class object {
+    default object {
         open public fun init<T>(name : T?) : Identifier<T> {
             val __ = Identifier<T>(name, false)
             return __