ingestion: review publication_state argument

Changing state directly in Base_contribute was only functional for the case
where metadata was discovered asynchronously. In the case of synchronous
discovery, the state was first changed state, and Document_convertToBaseFormatAndDiscoverMetadata
was executed - but this this was causing Unauthorized like this:

      Module script, line 10, in Document_convertToBaseFormatAndDiscoverMetadata
      - <PythonScript at /erp5/Document_convertToBaseFormatAndDiscoverMetadata used for /erp5/document_module/163>
      - Line 10
        return context.discoverMetadata(filename=filename,
    Unauthorized: You are not allowed to access 'discoverMetadata' in this context

because once we have already changed state, regular user no longer have
permission to access discoverMetadata, because that method needs ModifyPortalContent
permission.

Instead, of handling publication_state only in Base_contribute, treat it
like others user input parameter and change state during discovery.

Tests were also re-organised to move Base_contribute related test in testIngestion
and also to run Base_contribute tests as a non-manager user.