Update split resizing transition to match design

Remove the support of drawing side stage outline and update
OutlineManager to SplitDecorManager to help rendering decor view for
split screen like providing resizing hint.

Fix: 202740435
Fix: 202174975
Bug: 201653912
Bug: 200850654
Test: atest WMShellUnitTests
Test: manual check split resizing behavior

Change-Id: I4033255d8e2a94f69667ca1365b17da956816cde