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/j+k/javaStaticImport.kt

@@ -16,7 +16,7 @@ public class AsmUtil {
 // FILE: First.kt
 package frontend
 public class JvmDeclarationOrigin {
-    class object {
+    default object {
         public val NO_ORIGIN: JvmDeclarationOrigin = JvmDeclarationOrigin()
     }
 }