Use AaibReportPresenter if document type is AAIB

Allow the controller to switch which presenter and schema is used based on the document_type from the content api. This requires govuk_content_api to have an update to the ArtefactPresenter to pass through values for firstly the document_type and secondly all the attributes required for an AaibReport
Test document metadata appears on the page

Rather than duplicating the cucumber features across the board instead we can test the presenters directly and check that the controller uses the correct presenter. This addition helps us to check whether metadata attributes are being visibly displayed in the browser.
Spec should say 'I should see..' not 'I should the..'