Move some tests from boxWithStdlib/ to box/

Move those tests which do not require neither stdlib nor reflect

compiler/testData/codegen/box/dataClasses/toString/changingVarParam.kt

@@ -0,0 +1,11 @@
+data class A(var string: String)
+
+fun box(): String {
+    val a = A("Fail")
+    if(a.toString() != "A(string=Fail)") return "fail"
+
+    a.string = "OK"
+    if("$a" != "A(string=OK)") return a.toString()
+
+    return "OK"
+}