[K/N] Move special backend checks test sources to diagnostic tests folder

^KT-61564

compiler/testData/diagnostics/nativeTests/specialBackendChecks/objCInterop/t34.kt

@@ -0,0 +1,8 @@
+import kotlinx.cinterop.*
+import platform.darwin.*
+import platform.Foundation.*
+
+class Zzz : NSAssertionHandler() {
+    @ObjCAction
+    fun foo(x: NSObject, y: NSObject, z: NSObject) { }
+}