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/secondaryConstructors/accessToNestedObject.kt

@@ -0,0 +1,16 @@
+class A(val result: Int) {
+    object B {
+        fun bar(): Int = 4
+        val prop = 5
+    }
+    object C {
+    }
+
+    constructor() : this(B.bar() + B.prop)
+}
+
+fun box(): String {
+    val result = A().result
+    if (result != 9) return "fail: $result"
+    return "OK"
+}