More task improvements

[goose-life]

• Include the task type (code) in the task form for when individual tasks are created
• When an approved work has an amendment linked, create an Amendment task (with a confirmation modal / form)
• Include the timeline date in the task form
• Show the timeline date in the task detail view
• When an approved work is saved but doesn't have a publication document, create a Gazette task if it doesn't have one? (this seems kindof overkill)
• Add labels to be added to tasks in the approval form
• When an amendment's date is updated, also update any related task
• When an approved work is updated to principal = True, create an Import task (with a confirmation modal / form)