msglist: "Copy message text" button doesn't show "Message copied" popup when it should

In #713, @sm-sayedi noticed that the "Copy message text" button doesn't show our "Message copied" popup when it should. The message text is copied, but we just don't give feedback to the user about it.

In particular, it should be shown on iOS, and on Android versions before 13. (Android 13+ shows a native popup; see `copyWithPopup`).