Calculate desktop mode launch bounds for tasks launched into split

When a task is launched directly into multi-window, its activity type
is ACTIVITY_TYPE_UNDEFINED, which prevented
DesktopModeLaunchParamsModifier from setting its desktop bounds that
are used when the task is changed to freeform.
This change updates the early return in #calculate to allow tasks with
an undefined activity type to calculate the launch bounds.

Bug: 280830921
Test: launch app A, then B into split, exit split by dismissing B from
the divider, drag A into desktop, open B from the taskbar - verify the
freeform launch bounds are correct.
Test: atest DesktopModeLaunchParamsModifierTests

Change-Id: I5bdd7687a7db21f78239a30b50d4b29e4ab5e22f