Refactor giant SwDocTest::testModelToViewHelper() into smaller tests

This is to clear the way for following bugfixes which will add to /
amend these tests

Change-Id: Ie97aba72f1a4c7b1be37577b9bcab2b2f0750d17
Reviewed-on: https://gerrit.libreoffice.org/11808
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>