Introduce RUN-level OpenLineage events for dbt Cloud jobs

[br413]

Summary

• Emit START and COMPLETE OpenLineage run events for dbt Cloud job executions
• Reparent dbt model/test/source lineage events to the dbt Cloud job run instead of the Airflow task run
• Preserve Airflow task run as the parent of the dbt Cloud job run event

Hierarchy

Airflow Task Run
└── dbt Cloud Job Run
    ├── dbt Model
    ├── dbt Test
    └── dbt Snapshot

Test plan

• pytest providers/dbt/cloud/tests/unit/dbt/cloud/utils/test_openlineage.py
• CI provider tests for dbt-cloud and openlineage pass

Closes #68661

[br413]

Converting approach based on @kacpermuda's feedback on #68661: the RUN-level layer belongs upstream in OpenLineage (OpenLineage/OpenLineage#4720) first. Closing this in favor of the short-term OperatorLineage facet approach in the follow-up PR, then upstream invocation events.

[br413]

Closing in favor of the short-term facet approach (#70185) and upstream OpenLineage#4720 work.