✨ Non-interruptive Background Updates

We want CodeEdit to be evergreen, meaning it automatically downloads updates in the background. When the user closes or restarts, CodeEdit installs the downloaded update in the background. When an update is downloaded, the user gets a notification via notification center which allows them to install and restart then. If dismissed it will install on application close. There will be a "Automatically keep CodeEdit up to date" checkbox (enabled by default) that controls this behavior.