Cleanup old executions workflows & tasks

Morpheus mechanism to cleanup old workflows & tasks executions.

On a test environment after 3 years of running workflows and tasks,
it will useful to cleaup the old execusions. This will improve the database size and on the GUI the loading time for the page with execution history.

The persistent execution history is for auditing purposes. That said, you can purge these from the DB, but I don’t know the feasibility of adding it natively to the UI.