[Koha] Proposed fix for Bug 23039, holds obscuring check-in messages

I've been working on a possible solution to Bug 23039 (https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=23039). My proposal moves check-in messages into the confirmation modals. I've posted a brief video here of how it looks: https://zivotdesign.com/p/uploads/big/3d6b8a24067f27a834d03b8e104d7a40.mp4 If there is no popup (no hold confirmation, no transfer), messages and/or errors will be displayed onscreen just like they have in the past. I'd love to hear opinions about it, either here or on the bug report. Thanks! -- Owen -- Web Developer Athens County Public Libraries https://www.myacpl.org