[K/N][Tests] Move filecheck and cinterop tests to /native/

^KT-61259

native/native.tests/testData/codegen/fileCheck/kt49847_class.kt

@@ -0,0 +1,21 @@
+// TARGET_BACKEND: NATIVE
+// FILECHECK_STAGE: CStubs
+
+class C {
+    fun foo(x: Int) = x
+}
+
+// CHECK-LABEL: define %struct.ObjHeader* @"kfun:#box(){}kotlin.String"
+// CHECK-OPT-NOT: Int-box
+// CHECK-DEBUG: Int-box
+// CHECK-NOT: Int-unbox
+// CHECK-LABEL: epilogue:
+fun box(): String {
+    val c = C()
+    val fooref = c::foo
+    val result = fooref(42)
+    return if( result == 42)
+        "OK"
+    else
+        "FAIL: $result"
+}