Redesign Activity Details Page

[brrkrmn]

Summary

Redesigned activity details page according to the new design.

Depends on #1091

Closes #1092

Changes

• Activity actions menu is shown if the user is the creator of the activity or a staff member.
• Activity actions menu shows 'publish'/ 'unpublish' button if the user is a staff member.

Screenshots

To Do

• [ ] Use creators component to show activity creators
• [x] Make 'publish' and 'unpublish' buttons functional

[github-actions[bot]]

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