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

compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/classObject.kt

@@ -1,5 +1,5 @@
 class C {
-    default object {
+    companion object {
         <!CONFLICTING_JVM_DECLARATIONS!>val x<!> = 1
         <!CONFLICTING_JVM_DECLARATIONS!>fun getX()<!> = 1
     }

compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/classObject.txt

@@ -6,8 +6,8 @@ internal final class C {
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 
-    internal default object Default {
-        private constructor Default()
+    internal companion object Companion {
+        private constructor Companion()
         internal final val x: kotlin.Int = 1
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         internal final fun getX(): kotlin.Int