Refactor SpecialistDocument steps

As work continues, we've made the SpecialistDocument steps now just take
a document type in order to build paths.

The routes.rb is also changed to define both specialist_document_paths
and cma_case_paths. In the future, we should remove the
specialist_document_paths from the App completely.
Testing AAIB Report publishing workflow

With the addition of publishing AAIB reports to rummager, we need to
test this workflow.