Support audits to to assert shape of the data for sources and models

[harshvardhan-j]

SQLMesh currently has audits to assert the values of the underlying data, but not much in the ways of asserting the shape of the table.

This refers to checks for the presence / absence of columns, expected data types, number of columns, column order etc.

Such checks are useful for external models (sources in dbt) to ensure the data matches expectations and there is no drift, for e.g. new columns added / existing columns removed etc.

Given that SQLMesh also relies on "casting" data types, asserting against expected data types helps.

Expectations:

• Such checks are available
• These checks are scheduled as part of model runs

Helpful docs:

• https://github.com/calogica/dbt-expectations?tab=readme-ov-file#table-shape
• https://docs.soda.io/soda-cl/schema.html