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/casts/notIs.kt

@@ -0,0 +1,11 @@
+// TODO: muted automatically, investigate should it be ran for JS or not
+// IGNORE_BACKEND: JS
+
+fun foo(x: Any) = x !is Runnable
+
+fun box(): String {
+	val r = object : Runnable {
+		override fun run() {}
+	}
+	return if (!foo(r) && foo(42)) "OK" else "Fail"
+}