Issue 7469 - template mangling depends on instantiation order

https://issues.dlang.org/show_bug.cgi?id=7469

Normalize template value parameter arguments in `TemplateInstance::tiargs` at `findBestMatch`.

We shoul fix [Issue 12725](https://issues.dlang.org/show_bug.cgi?id=12725) first so the 7469 fix will break `test129()` in `runnable/test42.d` because of the bug.