Use WikiPage::makeParserOptions() where possible.

Use WikiPage::makeParserOptions() where possible.

- This is needed to for I90965346 ((bug 37453) Move
  $wgDisable(Lang|Title)Conversion to ParserOptions)
  because that change sets an option based on the Title,
  and I don't want to duplicate that to all ParserOptions
  that need it.
- Refactored ApiParse to have a WikiPage object available
  and changed some part to take advantage of having this
  object available. Also used ApiBase::getTitleOrPageId()
  to reduce code duplication.

Change-Id: Iec98e472af9c43d940f77261367a796b0d7b4b54