Add integration tests for the package

[b-per]

Adding some integration tests for the package. Those are manual for now and not part of CI/CD, but they can already be pretty useful for people wanting to add support for new adapters.

The tests are based on the example provided and test:

• the logic to add the exceptions column
• the generic test feature

I also updated the examples:

• i moved them outside of models, otherwise they were conflicting with the integration_tests folder, when importing the parent folder as package
• I changed some of the SQL syntax to make it work for all warehouses, removing ` and trailing , on the last line before from

Example for supported warehouses

Example for non-supported warehouse/adapter

[AxelThevenot]

I am really sorry for the delay, a lot of work to do on my side

I've gone through your two pull requests but not in detail yet

Do you want me to merge your Pull Request without a release or with a pre-release to wait for a deeper review before the release ?

And really hard job you made both for duckDB support and this integration test feature ! Impressive :)