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
Merged-In: I4033255d8e2a94f69667ca1365b17da956816cde
Change-Id: I4033255d8e2a94f69667ca1365b17da956816cde
222c9d3890