Allow rating without editing metadata

[AnonTester]

It would be great if ratings of a book could be changed without having to edit the whole metadata. Adding/removing from shelves as well as changing the read status can be done directly, but the rating needs to be done via the full metadata edit. When I've read a book, I remove it from my to-read shelf, set it to read and rate it. The last step is a bit cumbersome.
Thanks.

[ofostier]

I add the PR 3085