Lua: Expose localized cell names

In our current implementation, Cell class has only a name field, which stores a cell name from ESM. Such approach ignores translations from .cel files.

We can take in account translation files:

cellT["name"] = sol::readonly_property([](const CellT& c) {
    std::string str(c.mStore->getCell()->getNameId());
    if (!str.empty())
    {
        str = MyGUI::LanguageManager::getInstance().replaceTags(MyGUI::UString("#{sCell=" + str + "}"));
    }
    return str;
});

but I do not know if it would be better to add a new field or replace a current one.

Note that it is also possible to wrap text to MyGUI tag:

name = '#{sCell='..name ..'}'

But pure Lua widgets seem to do not replace tags.