feat: set query label session property in bq session

[ncbkr]

we want to use the SQLMesh session properties to attach labels to the BigQuery jobs. Using these labels we want to enable ourselves to

• map BigQuery jobs to SQLMesh models
• map BigQuery jobs to owners/users of SQLMesh

In the model definition, this would like as follows

session_properties (
    query_label = [
      ('label1', 'value1'),
      ('label2', 'value2'),
      ('label3', 'value3')
    ]
  )

This is currently not possible in an easy way since all jobs are created by the same service account.

The screenshot below displays the information about a BigQuery job created by sqlmesh to backfill a model. In the last line you can see the label my_session_property_key: my_session_property_value. This comes from the session_properties of the sqlmesh model definition. According to the google docs for BigQuery, all jobs that are run within a session inherit the labels set at the beginning of the session using SET @@query_label = <my_labels>

[izeigerman]

Thanks for your contribution! Can you please add some tests.

[izeigerman]

This looks really good! One last thing and this should be good to go. Thanks a lot for addressing the comments!

[georgesittas]

Thanks @ncbkr! Left a few final comments as well.

[georgesittas]

Looks great, well done! Also– thanks for your patience!

@izeigerman this is good to go from me, feel free to take another look.

[ncbkr]

Thank you as well for considering this change and providing feedback. This was very helpful. Happy to contribute to this great project

[izeigerman]

Thanks a lot for addressing comments!