Add "Delete Task" button to labeling page

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**Describe the solution you'd like**
I'm labeling relation extraction dataset. Now I can't delete current task when labeling, I have to return to the task list page, select it and delete it. I can only delete annotations when labeling. If there is a "Delete Task" buttion, it will be very convenient for the situation where we have to delete the current task for some reason.


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**Additional context**
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