Rework client facing submission information

[sauterl]

In order to improve both, the viewer and in addition, participating clients, we should address the following:

• Submission ID should be exposed upon submission
• Endpoint for submission information for participant
• Endpoint for submission information for task
• Dedicated view for all participants to visualise their submissions
• Dedicated view for logged in participants
• Expose more submissions information on client facing task state

[lucaro]

The way it's currently done is anyway not ideal, since the submission endoint returns a status object per submission, rather than per answer set.