Allow reviewers to give submissions quantitative ratings (ie x/5 stars)

This request comes from a PKP|PS client would would like to see the option for reviewers to rate a paper either 1-10 or 1-5 stars (similar to the reviewer rating given to a reviewer - see below).

They would like editors to be able to see reviewers’ ratings of a paper without having to go into each review to see it. E.g in the “reviewers” section, see below:

The author must not know or see this score.