Native: support Objective-C instancetype in more cases in cinterop

Objective-C has a special type, "instancetype". Generally, it is a type
that matches the method receiver type. So, if `Foo.foo` method returns
`instancetype`, then `Foo.foo()` would be of type `Foo`, while
`Bar.foo()` would be of type `Bar` (where `Bar` is a subclass of `Foo`).

Surprisingly, `instancetype` can be used not only as a return type, but
also somewhere inside a return type. cinterop wasn't ready for this.

This commit expands implementation of `instancetype` in cinterop to
cover more cases.

^KT-59597 Fixed

kotlin-native/Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/ObjCStubs.kt

@@ -388,7 +388,7 @@ internal abstract class ObjCContainerStubBuilder(
         methods -= superMethods
 
         // Add some special methods from super types:
-        methods += superMethods.filter { it.returnsInstancetype() || it.isInit }
+        methods += superMethods.filter { it.containsInstancetype() || it.isInit }
 
         // Add methods from adopted protocols that must be implemented according to Kotlin rules:
         if (container is ObjCClass) {