[ObjCExport] Support naming of nested classes

^KT-65204 Fixed

native/objcexport-header-generator/testData/headers/nestedInterface/!nestedInterface.h

@@ -0,0 +1,35 @@
+#import <Foundation/NSArray.h>
+#import <Foundation/NSDictionary.h>
+#import <Foundation/NSError.h>
+#import <Foundation/NSObject.h>
+#import <Foundation/NSSet.h>
+#import <Foundation/NSString.h>
+#import <Foundation/NSValue.h>
+
+NS_ASSUME_NONNULL_BEGIN
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunknown-warning-option"
+#pragma clang diagnostic ignored "-Wincompatible-property-type"
+#pragma clang diagnostic ignored "-Wnullability"
+
+#pragma push_macro("_Nullable_result")
+#if !__has_feature(nullability_nullable_result)
+#undef _Nullable_result
+#define _Nullable_result _Nullable
+#endif
+
+@protocol A
+@required
+@end
+
+@protocol AB
+@required
+@end
+
+@protocol ABC
+@required
+@end
+
+#pragma pop_macro("_Nullable_result")
+#pragma clang diagnostic pop
+NS_ASSUME_NONNULL_END

native/objcexport-header-generator/testData/headers/nestedInterface/Foo.kt

@@ -0,0 +1,5 @@
+interface A {
+    interface B {
+        interface C
+    }
+}