default -> companion: replace all mentions of default and default object

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

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