Replace the SelectionStrategy with a "Number of Judgements"

[epugh]

Is your feature request related to a problem? Please describe.
we have a single rater / mulitple rater support, but generally always pick multiple rather

Describe the solution you'd like
@david-fisher would like to instead have a default number, say 3, but you can tweak it. Max is the total number of judges. (show a warning message). So 10 judges, over 10 querys, would be featisdble. And good training.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
A use case would be "training new judges." Let's get ten judges to judge five queires five deep, and then we do IRR and talk about how to be better judges!