dags: Add a "data consistency" DAG

It runs consistency checks against production data.

dags/data_consistency.py

@@ -0,0 +1,27 @@
+import airflow
+from airflow.operators import bash, empty
+
+from dags.common import db, dbt, default_dag_args, slack
+
+
+dag_args = default_dag_args() | {"default_args": dbt.get_default_args()}
+
+with airflow.DAG(
+    dag_id="data_consistency",
+    schedule_interval="@hourly",
+    **dag_args,
+) as dag:
+    start = empty.EmptyOperator(task_id="start")
+
+    env_vars = db.connection_envvars()
+
+    dbt_test = bash.BashOperator(
+        task_id="dbt_test",
+        bash_command="dbt test",
+        env=env_vars,
+        append_env=True,
+    )
+
+    end = slack.success_notifying_task()
+
+    (start >> dbt_test >> end)