Add hideCurrentOverlays to UserActionResult.ShowOverlay()

This CL adds a parameter to ShowOverlay() that can be used to close/hide
some overlays when starting a new user action that shows an overlay.
This will be used by the dual shade to close one of the shades when
showing the other one.

I decided to put this property only in ShowOverlay because hiding
overlays during a ReplaceOverlay and HideOverlay could lead to a broken
state, and I didn't want to introduce more complexity if we don't need
these to support HideCurrentOverlays anyways.

Bug: 389618797
Test: atest OverlayTest
Test: atest PredictiveBackHandlerTest
Flag: com.android.systemui.scene_container
Change-Id: I2e6270e0181314b69d0ae051c957eb87e6f285de