[K/N] Deprecated freezing ^KT-50541

Starting with 1.7.20 freezing is deprecated. See https://github.com/JetBrains/kotlin/blob/master/kotlin-native/NEW_MM.md#freezing-deprecation for details.

Merge-request: KT-MR-6399
Merged-by: Alexander Shabalin <Alexander.Shabalin@jetbrains.com>

kotlin-native/backend.native/tests/codegen/enum/isFrozen.kt

@@ -2,7 +2,7 @@
  * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
  * that can be found in the LICENSE file.
  */
-
+@file:OptIn(FreezingIsDeprecated::class)
 package codegen.enum.isFrozen
 
 import kotlin.test.*

kotlin-native/backend.native/tests/codegen/initializers/workers1.kt

@@ -9,6 +9,7 @@ class X(val s: String)
 val x = X("zzz")
 
 // FILE: lib2.kt
+@file:OptIn(FreezingIsDeprecated::class)
 import kotlin.native.concurrent.*
 
 class Z(val x: Int)

kotlin-native/backend.native/tests/codegen/objectDeclaration/isFrozen.kt

@@ -3,6 +3,7 @@
  * that can be found in the LICENSE file.
  */
 
+@file:OptIn(FreezingIsDeprecated::class)
 package codegen.objectDeclaration.isFrozen
 
 import kotlin.test.*