Fix Version Constraint error when saving workflows

[ifranlaloe]

The constraint error was caused by making changes to "drafts" that were based on an older version. The draftVersion being returned by GetDraftAsync() in that case was that olderVersion.Version++ this would result in the new version already existing. And when saving the new Draft a constraint error was given by the database.

The solution I went for is as following:

1. For a Draft always work with the latest version
2. In case of a Publish a specific version will be fetched (or created if it's a non existing one)
3. In PublishAsync() the IsLatest property is never mutated. Only IsPublished
4. Change the order of saving, first save the new WorkflowDefinition, in case of any error the older WorkflowDefinitions do not get their booleans modified.

[dnfadmin]

All CLA requirements met.