Special:Log: Convert to HTMLForm

Special:Log: Convert to HTMLForm

* All Xml generation code has been removed.

* The LogEventsListGetExtraInputs hook now needs a form
  descriptor array and not plain HTML.
  See I37e0d3e81a46239750465b9299279fbbd7c7f87a.

* LogPager and LogEventList also take the $day parameter
  for 'From date (and earlier)' and pass it to getDateCond
  as well.

* Since FormOptions can't automatically extract the date
  from the request this is being done manually in the
  execute method of Special:Log using MWTimestamp.

Bug: T117737
Change-Id: Iba3c6aa5ac40dcdee0792c2d045b238b02d76521