Launch split task with correct UserHandle

PendingIntent#getActivity gets the owner UserHandle from the app
context. That makes the activity launch fail since the app only exists
in the work profile environment(secondary user).

This CL gets the correct Userhandle from Launcher and use
PendingIntent#getActivityAsUser to launch split task.

Bug: 242039471
Test: Launch Google chat by shortcut to enter split (work-profile)
Change-Id: Ie1db8a858bf9cee700cb3ff3a9e607a5d1dbad30