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/objects/objectVsClassInitialization_kt5291.kt

@@ -0,0 +1,24 @@
+public inline fun <T> T.with(f: T.() -> Unit): T {
+    this.f()
+    return this
+}
+
+public class Cls {
+    val string = "Cls"
+    val buffer = StringBuilder().with {
+        append(string)
+    }
+}
+
+public object Obj {
+    val string = "Obj"
+    val buffer = StringBuilder().with {
+        append(string)
+    }
+}
+
+fun box(): String {
+    if (Cls().buffer.toString() != "Cls") return "Fail class"
+    if (Obj.buffer.toString() != "Obj") return "Fail object"
+    return "OK"
+}