Finalising Drafts

[Seraphiana]

Add a functionality to finalise drafts in objective8. This should disable further draft submission, should include some sort of visual identification to tell that an objective is complete, and should disable most if not all further comments/questions being added to the objective. It should however preserve the page such that users can still see it.

1. Add a button for policy writers only to upload a final policy
2. Add a link to the final policy in the Objective's navigation bar
3. Default to showing the final policy
4. Final policy should not be interactable
5. Maintain "Compare with final draft" button