Johnny Depp has signed with CAA, the agency announced this morning. This is a shocker, and an exceptional development on multiple levels starting with the fact that stars long tenured with one agency, who’ve carried billion-dollar franchises, don’t often move. Some will simply read this as a big “get” for CAA in a continuing rivalry with UTA that ratcheted up last year when nearly a dozen CAA agents jumped to UTA and took clients including Will Ferrell and rising star…