[Windows] Taskbar progress implementation.

Thanks to @IDWMaster for base code.
[Windows] Only start taskbar progress on 0 progress.
[Windows] Refactor a bit so no duplicate code.
[Windows] TaskBar implementation works now.
[Windows] Taskbar status changes

It now only removes the completed event if MD is in focus.
Added support for unknown length tasks.
Error is now a full bar.
[Windows] Use IdeApp.Workbench window not MessageService.
[Windows] Don't add Focus as a taskbar progress event.