Fix issues with OCCLUDED -> GONE behind keyguard_wm_state_refactor.

We previously thought OCCLUDED -> GONE was not possible without transiting a *_BOUNCER state. However, apps can launch over an insecure keyguard without dismissing it using an intent flag. Once launched over an insecure keyguard (OCCLUDED), apps can then request dismissing the keyguard behind the app, which requires us to transition invisibly from OCCLUDED -> GONE.

This requires several changes:
- Listen to dismiss requests from OCCLUDED and start the transition.
- Hide lockscreen invisibly, behind the app, without triggering the going-away animation we usually start for * -> GONE.
- Cancel KeyguardViewMediator's doKeyguardLocked callback when dismissing. This is a temporary workaround for the fact that some KVM methods are still being called until we can fully migrate that class.

Bug: 278086361
Flag: com.android.systemui.keyguard_wm_state_refactor
Test: presubmit literally one hundred times (this causes hundreds of CTS test failures)
Change-Id: I9ef587aac4fafe368641d5f922b2af896662d6c2