[K/N][Tests] Migrate objcSmoke & objcTests tests

^KT-61259

native/native.tests/testData/interop/objc/tests/kt49455.h

@@ -0,0 +1,17 @@
+#import <Foundation/NSObject.h>
+
+// https://youtrack.jetbrains.com/issue/KT-49455
+
+@interface KT49455 : NSObject
+@end
+
+__attribute__((external_source_symbol(language="Swift", defined_in="sample",generated_declaration)))
+@interface KT49455 (KT49455Ext)
+- (int)extensionFunction;
+@end
+
+// Just to ensure that unavailable categories don't break anything.
+__attribute__((unavailable("unavailableExtensionFunction is unavailable")))
+@interface KT49455 (KT49455UnavailableExt)
+- (int)unavailableExtensionFunction;
+@end