Fix a few split rotation issues when the IME showing

- Fix an issue with the split bounds being wrong upon rotation. The target
  offset is relative to the actual task bounds and not the last y offset,
  so multiple changing IME insets changes in a row when rotating would
  set the window bounds of each task to be wrong, which affects the
  positionInParent of the task (relative to the single split root), which
  then results in the DefaultTransitionHandler positioning the task
  surfaces at the wrong position when the display rotation transition is
  actually played
- Fix an issue with the divider position being wrong upon rotation. The
  divider position is based on the IME state, but during rotation we can
  get numerous insets changes before the display rotation animation is
  played, so we should not reset the IME state.  In addition, due to races
  between the app/WM and the Shell, there may be no insets changes after
  the display transition is played, so we need to manually update the
  surface position after recreating the divider surface
- Restore handle view visibility & interactive state after recreating the
  divider view upon rotation

Flag: None
Test: Repeatedly rotate the device with the IME showing
Test: atest WMShellUnitTests
Bug: 299581029
Change-Id: Id43c388a27ae3be117857688f1ffd73a86bdea30
Signed-off-by: Winson Chung <winsonc@google.com>