[Web - Create New Course] Save as draft

[iarandrd]

As a content creator, I want to be able to save the course I'm creating as a draft, so I can finish it later

Update confirmation dialog to the figma template. Review text.

Figma template: https://www.figma.com/design/BCEVQYvMDrcBE9qqehr9HL/Mobile-Education-UI?node-id=5217-2723&t=Ye9AmGP5p93LiLc6-4

Acceptance Criteria:

• There should be a dialogue to confirm whether you want to save your course as a draft.
• As a content creator I should be able to cancel the action and confirmation by clicking 'cancel' or anywhere outside the dialogue box.
• When saving as a draft the course should maintain its status, e.g. 'draft'.
• If the course is already published the button should no longer be visible.