Connect Delete button in Author detail page

[karolina-siemieniuk-morawska]

After #532 is done, connect Delete button in Danger area section to endpoint.

[drjova]

Needs #532

[karolina-siemieniuk-morawska]

TECH NOTES:

1. Create new component DeleteWorkflow.tsx in /holdingpen-new/components directory. The component should receive workflow id as props and contain <Button className="font-white bg-error">Delete</Button> that opens confirmation modal. On confirming, it should dispatch deleteWorkflow action
2. In holdingpen.ts create a new action deleteWorkflow. It should send a DELETE request to /api/workflows/<id> endpoint and display success notification if delete was successful or error notification if not. After response from endpoint it should close modal.
3. In AuthorDetailPageContainer.tsx line 188 use this component.