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/controlStructures/continueInForCondition.kt

@@ -0,0 +1,12 @@
+// WITH_RUNTIME
+
+fun foo(): List<String>? = listOf("abcde")
+
+fun box(): String {
+    for (i in 1..3) {
+        for (value in foo() ?: continue) {
+            if (value != "abcde") return "Fail"
+        }
+    }
+    return "OK"
+}