backend/tests: Add blackbox tests from Kotlin JVM

Added tests from testData/codegen/box directory. There are blackbox tests
in other directories and they are to be added.

backend.native/tests/external/codegen/blackbox/properties/privatePropertyWithoutBackingField.kt

@@ -0,0 +1,17 @@
+class Test {
+    private var i : Int
+        get() = 1
+        set(i) {}
+
+    fun foo() {
+        fun f() {
+            i = 2
+        }
+        f()
+    }
+}
+
+fun box(): String {
+    Test().foo()
+    return "OK"
+}