Fix relaunch of freeform tasks outside desktop

When we are outside of desktop mode and core initiates a freeform
launch, if the task already exists in desktop we should move it to
fullscreen.

Bug: 352058911
Flag: EXEMPT Bugfix
Test: atest DesktopTasksController
Change-Id: Ided7af07eef8cc67a0b076cdbf55de0c3e61ef4a