feat: add queue action hooks

[mikehostetler]

Summary

• add an optional on_action hook to Bedrock.JobQueue configuration
• thread the hook through the consumer supervisor and manager
• invoke the hook inside the same transaction as queue complete/requeue/snooze actions
• normalize hook return values so queue behavior remains compatible

Tests

• mix format --check-formatted && mix test

[ccarvalho-eng]

blocking if this PR merges independently: when run_action_hook/5 returns {:error, reason}, this with returns an error tuple from inside repo.transact/1; Bedrock commits returned values unless repo.rollback/1 is called. PR #2 adds the rollback path, so I would either merge these as a stack or pull that rollback handling into this PR before merging #1.