Add SysUiProxy method to start transition on desktop task launch.

This forces the task to correctly start the TRANSIT_OPEN transiiton in
Desktop mode when launching an intent from the taskbar and prevent it
from opening in full screen.

Fixes: 361366053
Test: manual test
Flag: EXEMPT bugfix
Change-Id: I6d59705aa55745c3425266dacbb012dd4e2b1b03