Move some tests from boxWithStdlib/ to box/

Move those tests which do not require neither stdlib nor reflect

compiler/testData/codegen/box/topLevelPrivate/syntheticAccessor.kt

@@ -0,0 +1,11 @@
+package test
+
+private val prop = "O"
+
+private fun test() = "K"
+
+fun box(): String {
+    return {
+        prop + test()
+    }()
+}