BISERVER-7665 - Code duplication: mantle_confirmBackgroundExecutionDialog (jsni) defined twice

What was done:
1) Removed dupllicated methods runInBackground and confirmBackgroundExecutionDialog
2) Switched SolutionBrowserPanel to use dialog from ScheduleHelper
Merge pull request #1147 from kolinus/BISERVER-7665

BISERVER-7665 - Code duplication: mantle_confirmBackgroundExecutionDialog (jsni) defined twice