[code_review] Generate comments with multiple models/configs or multiple approaches

[marco-c]

An ensemble to generate more comments, with a filtering step to only output actually unique ones.
For example, GPT-4o + Mistral. Or, GPT-4o with the patch in the default order + GPT-4o with the patch in random order.

4028e2d was the first step for this.

This depends on #4580 for the evaluation.
This also depends on #4582 and #4587 to choose what to put in the mix.