* create a MainContent and SidePanelContent containers for layout
this creates these two new components for handling layout more cleanly. It also allows us to put in common components into main layout, like sandbox expiration notification
* use MainContent and SidePanelContent in current pages
this brings in the two new components and wraps the page contents in these. This also allowed us to clean up and remove unused/no needed styling code
* add MainContent component to user settings page and clean up user settings component
this cleans up the user settings page to follow the panel convention we have as well as adds the MainContent component to this page
* add MainContent component to team pages
* update Sandbox gate to render optional component when in sandbox mode and add to MainContent
* add call to sandbox api to get expiry time
this adds a conditional call when the user is in sandbox mode to get the expiry time of the instance
* fix sticky elements on settings pages to work with sandbox expiry message
* fix e2e test after MainContent refactor
