Define procedure to check impact of merge requests in terms of efficiencies and throughput

The idea is to formalise some of tests and checks which need to be performed before accepting a merge request which changes either the efficiency of the reconstruction and selections or has an impact on the throughput. These tests can then also form the basis of a short presentation explaining the idea behind the changes and its impact.

This procedure should help in a situation with two different reco algorithms being proposed with different performances and where one is not obviously better than the other or when an algorithm undergoes significant changes. If the metrics are clear and apply to everyone equally, we probably save ourselves some headaches in those cases.