Add the concept of a 'stage'

We currently have a 'status' that indicates if a Service is being deployed, but we would also like to be able to indicate the progress of the Deployment pipeline through the various stages. Many deployments have some form of a Pipeline that might be as simple as `stages = ['build', 'deploy']` while some are much more complicated such as `stages = ['lint', 'test', 'build_docker_image', 'push_image_to_ecr', 'create_new_task_definition_version', 'update_service_with_new_task_definition_version', 'force_new_deployment_on_ecs_service', 'smoke_test', 'regression_test', 'completed']`

While it is nice to have a status of 'Deploying' it would be more helpful to see what stage of the pipeline the deployment is at.

Tracking the stages also allows us to log how long each stage typically takes and graph it over time for easier viewing of where bottlenecks may occur within the pipeline itself, and give the user the knowledge to target those stages for improvement.

I see this being an extra field in the log, as well as being a field item in the service as well.

未指定檔案或測試。首先定位 Service 模型、部署狀態處理邏輯和日誌寫入入口，然後追蹤一次部署如何通過其管線。完成標準是：可以在 service 和部署日誌中表示各階段，並且可以取得階段耗時以追蹤瓶頸。

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