Add a new section to show system data information

[wlorenzetti]

Checklist

• [x] I've searched through the current issues to make sure this feature hasn't been requested already.

Motivation

It could be useful add a section/page to show information about system data, i.e. QGIS server version runnig, Python version used, Libraries version etc.

Suggested solution

Add a new item to right G3W-ADMIN menu:

to show a overview like this:

Alternatives considered