Update latest ActivityRecord#mLaunchSourceType if possible.

The launch source can change when the top activity is launched from
recents or home, make it updatable so the style and theme used for
starting window can be correct.

Flag: EXEMPT bugfix
Bug: 340401554
Bug: 353187744
Test: atest EnsureBarContrastTest WindowInsetsControllerTests
Test: launch test app then kill app process, verify system will show
starting window when launch app again.

Change-Id: Ie7eedcea7a81ac5be835f04993ebb291ca6c0672