Runtime/Behavior Changes

Changed the design of the notification banner when background install fails.
When the user closes CET, CET will now prompt the user to cancel any currently running updates before proceeding to exit CET.
Previously, the background install process attempted to register catalogues during the customizations Extension initialization step, which occurs as a side effect when the installer performs a sanity check by loading the install extensions. In some cases, this could result in the main CET instance encountering locked catalogue databases if they were in use by the background instance (and vice versa).
Since catalogue downloads are managed by the foreground instance, the background instance is now no longer connected to the downloader. Manufacturers should note that any code using while loops to delay extension initialization until catalogue downloads complete may need adjustment, as this is not recommended behavior (or at least to avoid this during runningInInstallAndCloseMode).