[cleanup] Add a separate method delete_redirect()
[cleanup] Add a separate method delete_redirect()

- Both actions double and delete uses code to delete a page but for
  double action this part is not enabled yet neither in core not in compat.
  But this should be solved later and consider that a redirect loop may be
  created by accident or by vandalism and the page has a version history.

  Anyway we could split off that code and recycle it. This prevents code
  duplication and gives a better readability.

- change action comment because deleting is not the only way to solve
  broken redirects

Change-Id: I49f39bae584b7c62fd1a99cf80407a5987d9a5a3

PersianWikipedia/pywikibot-core,magul/pywikibot-core,happy5214/pywikibot-core,magul/pywikibot-core,npdoty/pywikibot,wikimedia/pywikibot-core,hasteur/g13bot_tools_new,h4ck3rm1k3/pywikibot-core,npdoty/pywikibot,wikimedia/pywikibot-core,h4ck3rm1k3/pywikibot-core,hasteur/g13bot_tools_new,Darkdadaah/pywikibot-core,jayvdb/pywikibot-core,Darkdadaah/pywikibot-core,jayvdb/pywikibot-core,hasteur/g13bot_tools_new,happy5214/pywikibot-core