Add configurable ranking size

[Lordfirespeed]

Describe the feature you'd like

Rankings should require and be limited to a configurable number of teams, e.g. 5.

Judges should not be permitted to submit their ranking prematurely (i.e. before seeing 5 teams)

The idea is that this would reduce variance introduced by judges acting more harshly towards the start of a judging session.

We need to add functionality on the administrator side to 'end judging' which

1. Allows judges to finish viewing their current project
2. Stops giving judges new projects
3. Forces submission of rankings, even when a ranking is incomplete (smaller than the ranking size)

Pre-existing Issue or Justification

No response

Additional context

No response