Refactor: Move wiki_tools function that use a mwclient.Site argument to osw.wtsite.WtSite as methods

[LukasGold]

• osw.wtsite relies on an import of wiki_tools. Therefore, it is not possible to create wiki_tools functions that accept both, mwclient.Site and osw.wtsite.WtSite objects.
• Further, it is rather non-intuitive to have to access the OSW.site._site attribute to get a mwclient.Site object which can be passed to the wiki_tool functions in questions.

Bottomline: We should do a refactor to move most functionality of wiki_tools that have a mwclien.Site attribute to osw.wtsite.WtSite methods