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/reified/instanceof.kt

@@ -0,0 +1,16 @@
+// TODO: muted automatically, investigate should it be ran for JS or not
+// IGNORE_BACKEND: JS
+
+// WITH_RUNTIME
+
+inline fun<reified T> isinstance(x: Any?): Boolean {
+    return x is T
+}
+
+fun box(): String {
+    assert(isinstance<String>("abc"))
+    assert(isinstance<Int>(1))
+    assert(!isinstance<Int>("abc"))
+
+    return "OK"
+}