pkp/pkp-lib#9456 Add private notes for reviewers

[nibou230]

How to test?

This test can only be done if the OJS instance has multiple journals on it.

1. Ensure the user on which notes will be used is at least associated to 2 journals.
2. As an editor In journal A: add the reviewer to a submission, then clic on Editorial notes in the reviewer menu. Add both a public and private notes
3. As an editor in journal B: add the same reviewer to a submission. In the add user window, display all information about the reviewer: only the public editorial note add by Editor of journal A is displayed.
4. Clic on Editorial notes in the reviewer menu. Add a private note.
5. As an editor In journal A, add the same reviewer to a new submission, in the add reviewer window, display reviewer details, you should see the private notes of Journal A, not the one from Journal B.

[asmecher]

(Not a big deal -- but the indentation in the XML files should use tabs for consistency.)