Make PIP into split screen

Improve the interaction between split and PIP. e.g support drag and
drop pip app into split, start the pip into split, start Intent and
task into split.

Bug: 259161859
Test:  PIP is activated and drag pip app into split.
Video :
https://drive.google.com/file/d/10VdfV7jfGHGRLrEdxAIWFKPhBVgwFTrI/view?usp=share_link&resourcekey=0-jZD7-EzUGc95WQIND3Jxrw

Change-Id: I2d72eeb2a799e94bb53fe42ce2b439644ec8520e