Remove group-based info from projects page

Remove group-based info from the projects index page (/projects, not within a course edition). This should be instead only shown in the groups page

• Rename 'My projects' to 'My proposals'
• Hide this tab for anyone who cannot create projects
• Remove 'Participating projects', 'Coached projects', 'Interested projects' (and experiments, but check whether those appear on the my groups page) from that page
• Move 'Projects you are interested in' from course edition project index page to a separate tab (think about this)