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/when/integralWhenWithNoInlinedConstants.kt

@@ -0,0 +1,28 @@
+// TODO: muted automatically, investigate should it be ran for JS or not
+// IGNORE_BACKEND: JS
+
+// WITH_RUNTIME
+
+fun foo1(x: Int): Boolean {
+    when(x) {
+        2 + 2 -> return true
+        else -> return false
+    }
+}
+
+fun foo2(x: Int): Boolean {
+    when(x) {
+        Integer.MAX_VALUE -> return true
+        else -> return false
+    }
+}
+
+fun box(): String {
+    assert(foo1(4))
+    assert(!foo1(1))
+
+    assert(foo2(Integer.MAX_VALUE))
+    assert(!foo2(1))
+
+    return "OK"
+}