Feat(dbt): Add support for transaction in dbt pre and post hooks

[themisvaltinos]

This adds support for transaction in dbt pre and post hooks. By default hooks are executed inside of the same transaction as the model being created. Hooks that need to run outside a transaction are for example when executing a VACUUM in Redshift or inserting into an audit table at the start of a run where the insert should persist even if the model fails. Running the hook outside a transaction ensures it won’t be rolled back.

These are set in a dbt project either with the before_begin and after_commit macro:

{{
  config(
    pre_hook=before_begin("SQL-statement"),
    post_hook=after_commit("SQL-statement")
  )
}}

or by setting the transaction flag in a dict:

{{
  config(
    pre_hook={
      "sql": "SQL-statement",
      "transaction": False
    },
    post_hook={
      "sql": "SQL-statement",
      "transaction": False
    }
  )
}}

By default and without setting the transaction the hooks are executed inside the transaction.

Docs: https://docs.getdbt.com/reference/resource-configs/pre-hook-post-hook#transaction-behavior