[FEAT] Improved Site.sametitle

This improves the Site.sametitle comparision by the following features:
- It uses (if available) the case-sensitivity option defined by the
  namespace
- It replaces underscores and spaces by only one space. So 'Fo__ar',
  'Fo_ar' and 'Fo ar' are all the same.
- It works with servers which don't have a namespace which is empty.

Bug: 69118
Change-Id: I0b57ea6d7014b4ddfd8ceafbd859594b021e92b4