[5.1] Convert mod_frontend to service provider

[joomlaweby]

Summary of Changes

Converts the frontend link administrator module to service provider.

Testing Instructions

1. Make sure you have administrator module mod_frontend published
2. You should see module output

Actual result BEFORE applying this Pull Request

Module works as expected

Expected result AFTER applying this Pull Request

Module works same way as before applying pull request

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[fgsw]

I have tested this item ✅ successfully on 3671f92

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/42853.}

[viocassel]

I have tested this item ✅ successfully on 3671f92

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/42853.}

[richard67]

RTC

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/42853.}

[LadySolveig]

Thank you @joomlaweby and also for testing @fgsw @viocassel