Feature Request - Synchronised clip notification

Hope I'm doing this right. I've copied part of the last post from the original issue as it clearly states what's required. When a clip of any sort is added to a synchronised/shared tab (in my case via my NAS in a shared folder which all users can access) a notification is presented. I'm running Windows 10, so I originally envisaged a standard Windows 10 banner notification in line with many other apps that have now added this functionality, but any kind of notification would be useful.

Last post from [original thread](https://github.com/hluk/CopyQ/issues/866):

As for CopyQ, I think a reasonable feature request would be for CopyQ to notify you if one of the items in your tab has been changed/added externally. Such notifications are common among other programs. However, CopyQ should not in my opinion give a system-wide notification in such a case (I have not seen any other application do that, except Dropbox whose purpose is to manage file and folder changes). It would just be something that you see when you open CopyQ. If you would like to make this request, please open a separate issue."