Merge boxWithStdlib testData into box, delete BoxWithStdlib test

compiler/testData/codegen/box/when/enumOptimization/functionLiteralInTopLevel.kt

@@ -0,0 +1,17 @@
+enum class Season {
+    WINTER,
+    SPRING,
+    SUMMER,
+    AUTUMN
+}
+
+fun foo(x : Season, block : (Season) -> String) = block(x)
+
+fun box() : String {
+    return foo(Season.SPRING) {
+        x -> when (x) {
+            Season.SPRING -> "OK"
+            else -> "fail"
+        }
+    }
+}