Make pip task could be enter split

This CL migrate the pip to split flow. Before this CL, split side
always start a enter transition after drop app. But pip side also
start another transition when they got restart attemp and lead to
two transition here(split enter transition will got exception case
here due to the target pip task didn't include in transition change
which caused by it already on front). In this case, split should just
launch the intent and let pip side to handle itself transition.

This CL only handle start single intent case, need to take
another look to handle all cases such as shortcut, or open
two intents, tasks case.

Bug: 282134052
Bug: 282902244
Bug: 284089421
Test: manual
Test: pass existing tests
Change-Id: Iaf4f5e305ea8f46be786f0316b4f8a3d2a14c3e9
Merged-In: Iaf4f5e305ea8f46be786f0316b4f8a3d2a14c3e9