Add a link to the Status report on the update-complete page

[jenlampton]

When I'm doing updates to my Drupal sites, I like to check the status report immediately after running the update to check and see if I need to do anything else (like update libraries or adjust new settings). The current workflow for running updates makes this process less than ideal since I need to return to "Administration pages" before I can get to a menu that would allow me to navigate to the status report page.

Adding a link to the status report directly from the update page would improve things, assuming my use-case is common.

[jenlampton]

See related: #288

[quicksketch]

Thanks! Merged in backdrop/backdrop#392.