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/diagnostics/tests/resolve/invoke/kt3833-invokeInsideNestedClass.kt

@@ -1,4 +1,4 @@
-//KT-3833 Invoke method not working inside class object?
+//KT-3833 Invoke method not working inside default object?
 package m
 
 class Either1 {
@@ -26,7 +26,7 @@ object Foo{
 }
 
 class C{
-    class object {
+    default object {
         fun f(){
             Foo.v()
         }

compiler/testData/diagnostics/tests/resolve/invoke/kt3833-invokeInsideNestedClass.txt

@@ -8,7 +8,7 @@ package m {
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 
-        internal class object Default {
+        internal default object Default {
             private constructor Default()
             public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
             internal final fun f(): kotlin.Unit

compiler/testData/diagnostics/tests/resolve/nestedCalls/analyzeArgsInFreeExpressionPosition.kt

@@ -1,5 +1,5 @@
 class A {
-    class object {
+    default object {
 
     }
 }

compiler/testData/diagnostics/tests/resolve/nestedCalls/analyzeArgsInFreeExpressionPosition.txt

@@ -9,7 +9,7 @@ internal final class A {
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 
-    internal class object Default {
+    internal default object Default {
         private constructor Default()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int