Move some tests from boxWithStdlib/ to box/

Move those tests which do not require neither stdlib nor reflect

compiler/testData/codegen/box/callableReference/function/extensionFromClass.kt

@@ -0,0 +1,7 @@
+class A {
+    fun result() = (A::foo)(this, "OK")
+}
+
+fun A.foo(x: String) = x
+
+fun box() = A().result()