Add ability to set service login upon starting a service. Prompt only appears if the current service login is different than the installation's.

To do: Update "Databases & Logins" tab when service login is set.
Installation logins load once more!
(cherry picked from commit 364faf528418f62615374dfe8954cc0e2f1071b9)
Update service login on Database&Logins tab when you switch to it. To do: Fix "Stop All Services" triggering the popup