Determine whether to support activities in multi window (9/n)

When a Task is detached but is still stored as a recent Task, it should
be allowed to launched into split screen.

Bug: 176061101
Test: atest WMShellFlickerTests:EnterSplitScreenFromDetachedRecentTask
Test: atest WmTests:RecentTasksTest
Change-Id: Ic72901ca76f4acb6e68926062675ecc290b399be