UX: Add button to clear scheduled publish/unpublish state

Thanks for the suggestion, yes it's a nice idea. If anyone would like to progress it, please go ahead.

A 'clear' button in Scheduler would remove the dates and also remove the selected publish/unpublish state if using SCMI → . This issue title says 'scheduled publish/unpublish state' but the issue summary says 'clearing the date/time and publishing state '. I think this is therefore a duplicate of the earlier issue ✨ UX improvement suggestion > A cancel button to easily remove a scheduled publication date from a node Active