K1: Implement a checker that disallows to have different member scopes for expect open and its actual

^KT-22841 Fixed
Review: https://jetbrains.team/p/kt/reviews/11603/timeline

The commit also introduces `@AllowDifferentMembersInActual` annotation in
stdlib which allows to suppress the diagnostic

libraries/stdlib/src/kotlin/annotations/AllowDifferentMembersInActual.kt

@@ -0,0 +1,37 @@
+package kotlin
+
+import kotlin.annotation.AnnotationTarget.*
+
+/**
+ * Kotlin reports a compilation error for cases when non-final `expect class` and its counterpart `actual class` have different set of
+ * non-private members (e.g. when a new member declared in `actual class` that wasn't presented in its `expect class`, or when
+ * modality is different).
+ *
+ * By marking `actual class` with this annotation, you suppress the compilation error mentioned above.
+ *
+ * ## Safety Risks
+ *
+ * Using this annotation causes undefined behaviour, it's not known what can break because of that. Be prepared that at some point this
+ * annotation might become deprecated, and you'd need to migrate your code.
+ *
+ * If you use this annotation and can't migrate, consider describing your use cases in
+ * [KT-22841](https://youtrack.jetbrains.com/issue/KT-22841) comments.
+ *
+ * ## Migration
+ *
+ * Please consider the following alternatives:
+ * - Make members in `expect class` and `actual class` the same
+ *     - If the member was declared only in `actual class` then you'd need to declare it in the `expect class` as well
+ *     - If the member is already declared in the `expect class` then make sure that the member is the same in the `actual class` (modality is
+ *       the same, visibility is the same, return type is the same, etc.)
+ * - Make the `expect class` `final`. You might need to rewrite your code to use composition instead of inheritance.
+ * - Mark the members under the question as `private`
+ *
+ * [AllowDifferentMembersInActual] is supposed to be used for the transition period.
+ */
+@Retention(AnnotationRetention.SOURCE)
+@Target(CLASS, TYPEALIAS)
+@MustBeDocumented
+@ExperimentalMultiplatform
+@SinceKotlin("1.9")
+public annotation class AllowDifferentMembersInActual

libraries/stdlib/src/kotlin/reflect/KClass.kt

@@ -32,4 +32,7 @@ public expect interface KClass<T : Any> : KClassifier {
     @SinceKotlin("1.1")
     public fun isInstance(value: Any?): Boolean
 
+    override fun equals(other: Any?): Boolean // KT-24971
+
+    override fun hashCode(): Int // KT-24971
 }