Login feedback if user do not have offline access

[carlitorweb]

Pull Request for Issue #39559

I used the core string JLIB_LOGIN_DENIED = Your access has been denied. But I think we should create a new one just for this message

Summary of Changes

PlgAuthenticationJoomla verified is a valid user who try to access, but not check the permission of the offline mode.

Testing Instructions

Set your site in offline mode. Go to the frontend and try login with a user who have the permission Offline Access = Not allowed

Actual result BEFORE applying this Pull Request

The user cant login, but not message show up of why cant login

Expected result AFTER applying this Pull Request

The user cant login, but a message show up of why cant login

[richard67]

@carlitorweb As the check added by this PR is in the else part of an $this->app->isClient('administrator') check, it doesn't only apply to the site but also to other non-admin clients like api and cli. Is that intended?

[carlitorweb]

@richard67 For API dont matter. Right now, an unique Bearer token or credentials need be provided in the request. The later have his own separate routine for authenticate the user Joomla\Plugin\ApiAuthentication\Basic\Extension\Basic (by the way is almost the same as PlgAuthenticationJoomla)

I did not interact much with the CLI yet, but I tested for example, when offline the site I could add a new user trought the CLI without problem. I not think so far this change affect the CLI application. Anyway, let me kown if anything need be changed.

[carlitorweb]

@richard67 can you run the drone again, not sure why fail

[Quy]

I have tested this item ✅ successfully on 0f48b71

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/39561.}

[viocassel]

I have tested this item ✅ successfully on 0f48b71

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/39561.}

[Quy]

RTC

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/39561.}

[fancyFranci]

Thank you for making it easier for the users!