BE - Update metabase.automagic-dashboards.core/source to return a model card rather than its underlying table.

[markbastian]

• This is a small change, seems to break no unit tests, and ensures that the number of available fields to create cards from is not oversampled (e.g. We don’t see cards generated from the underlying table)
• Note that the number of fields is undersampled - The reason why is unclear
  • I think it has to do with how our dimensioning system works and this is a separate issue
• Add meaningful unit tests (beyond “This made lots of cards”). Current unit tests set up a scenario (generally not well documented as to why or what the scenario is about) and assert that many cards were created and none failed certain constraints (has name, correct cardinality, correct url, etc.).
  • A key deliverable for this task is to provide a more meaningful test setup and result than the above
  • We should assert both positive and negative field values
    • What dimensions were used
    • No data that is not visible is used
    • Models should produce links to related entities if the entity fields are visible

[markbastian]

Starting state. Note that we don't select a time column:

If we x-ray this we get the following. Note that "Created At" is not part of this card, so this is showing too much data. You can, however, Zoom Out to the table on the right, which is expected.

By adding a simple rule for models based on tables, we get the following behavior: