Publishing a metastore does not change revision date

[swirtSJW]

Current Behavior

In Metastore Data.php the function setWorkflowState() does not add a revision date. This creates a confusing situation where a draft made weeks ago and a publish today shows the two revisions with the same date.

This comes from an odd drupalism where if a revision has not timestamp set it uses the timestamp from the previous revision, creating confusion throughout the land.

Calling
$entity->setRevisionCreationTime(<timestamp here>);
right before the $entity->save() will resolve this.

Time stampery will need something like \Drupal::time()->getCurrentTime()

Expected Behavior

• When a dataset publishes or goes through some other status change, the revision list tells the true story.

Steps To Reproduce

1. Save a datset in draft.
2. wait 10 minutes
3. Publish it using the metastore publish function
4. View the revision log. shows the same date and time.