Fix some notification badge related issue

* In some languages like persian, the number 0 is represented as '.', we can't compare
  '.' with either 0 or '0' to detect the no-notification status of the badge

* The markread API doesn't respect uselang param, it would return 0 instead of . in a url with uselang=fa

Note: we need to provide raw and formatted count in the API since client side javascript
      doesn't provide fancy function like $wgLang->formatNum()

bug: 54575

Change-Id: I0a49828253ec346ed27c5b9a976f8bdff4e1fa90
Merge "Fix some notification badge related issue"