Shortcut source - support for new data model

[thomas-gerber]

Context

A user set up the source with v3, the token and nothing in public project ID.
No stories or epics were read, even though the credentials have access to stories and epics.

Initial analysis

1. It seems now that the main entity a Story belongs to is not the Project anymore, but the Workflow (see here and here).

2. The current solution where we get Stories through search seems very fragile:

• It is not part of the library we use (which is not on the recommended list)
• It doesn't appear to paginate through the results

Success criteria for this issue

i) The workflow is the entity mapped to tms_project; project may now be the tms_taskboard
ii) The connector shall pull all stories and epics that the token has access to