Fix Taskbar unlock transition

- There are multiple signals that come just after FLAG_DEVICE_LOCKED
  is removed, and those should still be considered part of the unlock
  transition. We already did this for TaskbarStashController so I copied
  it to TaskbarLauncherStateController.
- Also animate when changing SYSUI_STATE_OVERVIEW_DISABLED, since this
  happens when the device is locked/unlocked and changes the visibility
  of TaskbarView icons.

Test: manually unlock over both home screen and in-app, verify clean
transition without jump (e.g. Hotseat is immediately visible as part of
Workspace, and Taskbar fades in during unlock to an app)
Flag: EXEMPT bug fix
Fixes: 364586744

Change-Id: If0497fcc17bb0ec44294c4ea1163104b4d8be459