issue #5409
- change persistent/passive notification status to alert/notification
- replace showSuccess/Info/Warn/Error with showNotification/showAlert
- fix and clean up notification/alert components
- Adds gh-view-title component to implement mobile menu button for titles on any page
- Refactors the `content-cover` out into the application template
- Fix various z-index issues with content-cover and gh-alert
- Move `.settings-menu-expanded` application view state from body to `.gh-viewport`
- Unify nav menu / mobile menu actions and code