Add logview url for dtm log collection (#2938)
Add logview url for dtm log collection (#2938)

* Collect step's output to given file

* add SQLFLOW_WORKFLOW_STEP_LOG_FILE evn to control log path

* Add graceful exit time for step

* Add wait to exit time for step

* Add step container init code

* remove unused print

* Add logview url for dtm log collection
sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow