Create new stellar-etl-airflow to create dbt seed files

[chowbao]

Currently there are dbt commands in stellar-etl-airflow for build and run but there isn't a generic dbt * command.

Option to either create a new generic dbt command operator or just make a specific one for dbt seed to materialize the seed tables.

Because seed tables aren't updated very often there is no point in creating an airflow DAG that runs on a schedule. We should make a dbt_seed_dag that only runs on manual trigger